You make a good point about Drallig, however lets also consider that by that point as Darth Vader he had become immensely powerful. Before the war he was already a very formidable lightsaber duelist able to go toe-to-toe with Count Dooku, whom he defeated aboard the Invisible Hand. And Dooku was far superior to Drallig in terms of skill with a lightsaber, he was second only to Yoda and Windu.
Now you could attribute that growth in power to the Clone Wars but as you say fighting hordes of battle droids would have done little to hone is lightsaber skill, only Ventress, Dooku and Grievous provided any sort of challenge - and he did not confront them frequently. We can just as much attribute his growth in power to practice and study. He also learned to augment emotions into his power, rather than let them unbalance him as other Jedi had. And when he finally embraced the dark side his skill in Form V became immensely amplified.
And concerning the other arguments you brought up
Darkondo refrains from listing them all in detail for good reason, because there were so many. Just look them up on Wookieepedia, they were all renowned and highly skilled lightsaber duelists:
Mundi was an extremely skilled fighter with the Jedi weapon.
Plo Koon was a powerful Jedi Master and the mysterious Sith Lord Darth Maul considered him to be one of the greatest Jedi warriors of his time though they never dueled one another...He was also a master of the fifth form of lightsaber combat, Djem So/Shien. Master Plo was considered amongst the most skilled swordsman in the Jedi Order, being capable of fending off even Asajj Ventress while being encumbered by a broken arm
Having trained as a Jedi Guardian, Saesee Tiin possessed exceptional prowess with a lightsaber
A master practitioner of Shii-Cho, Kit Fisto was considered to be one of the best swordsmen in the Jedi Order.
However, he was primarily known as a master lightsaber duelist. Mace Windu himself, considered one of the greatest duelists in the Order's history, found Kolar's abilities considerable.
Obi-Wan Kenobi was one of the greatest lightsaber duelists of his time...Ten years study into Form III resulted in an advanced skillset, and Kenobi became one of the most esteemed swordsmen in Jedi history...In addition to Soresu, Kenobi would also master and incorporate elements of Shii-Cho and Niman into his fighting style, as well as appearing to have been well versed in the art of Jar'Kai dual-blade combat
Shaak Ti was well versed in several forms of lightsaber combat. Considered one of the finest swordswomen of the era, her colleagues regarded her as one of the most cunning warriors of the day.
Luminara Unduli possessed power that very few Jedi were able to overcome. She had amazing lightsaber skills, as she was a master of Form III and had some skill in Form V. Not only were her lightsaber skills superb, but she had also trained herself to become so incredibly flexible that she could easily twist to evade almost any attack that she did not block with her green lightsaber.
Aayla Secura was trained as a Jedi Guardian, leading her to focus more on her combat skills, becoming an impressively skilled fighter. She mastered the fourth form of lightsaber combat, Ataru, and had some skill in Form V, as well as being a practitioner of Jar'Kai.
Before his resignation, Dooku was known as one of the most skilled duelists and lightsaber instructors in the Jedi Order. He was the Jedi Temple's most agile swordmaster and instructor...Count Dooku was one of the finest practitioners of Makashi in his day, mastering the form at its highest levels...Dooku's practical application of the form was exemplary; his skills were surpassed only by Yoda, and only Mace Windu was credited as Dooku's equal.
Bulq was best known among the Jedi for his skill with the lightsaber; he was known to have achieved mastery of all the lightsaber combat forms and was considered among the Order's greatest swordsmen.
Anakin Skywalker was trained by the Order's most promising Jedi Knight, Obi-Wan Kenobi. Through him, Skywalker would inherit a rich tradition of lightsaber training. Skywalker's style featured elements of many masters, making him outstandingly talented, even at a very young age.
~ Wookieepedia, most sourced from Star Wars
Also just because a Jedi has taken part in battle does not make them "by default, more experienced and skilled in lightsaber combat since they are constantly fighting against lightsaber wielding opponents" - to accept that we would have to accept your entire premise and this argument wouldn't be taken place now would it? And those Jedi were not as highly skilled as you claimed as Malgus defeated and destroyed them.
I also fail to see your point concerning Force abilities. It is obvious and nothing short of a canon-fact that lightsaber mastery depends on a strong affinity (may I stress affinity, not knowledge) in the Force. Not just for heightened sense and awareness, but to augment ones speed, reflexes and ability in precognition. But my point more is that war unbalances a Jedi's connection to the Force, and so their concentration, and their ability to draw upon all of the above, are hampered - they become weaker. A point you have yet to address. A Jedi living in peace time is at peace inside, and therefore can better wield a lightsaber. Note that sensitivity and awareness and Force channeling abilities stem from the same source. If anything sensitivity and awareness are more negatively effected by unbalance, caused by conflict. And concerning Dun Moch, its not just psychological warfare, by encouraging a Jedi to embrace their emotions, they cannot draw on the light side of the Force as easily, it hampers them. War has the same effect as Dun Moch, its a psychological war of sorts. And just to clarify, affinity in the Force (gained through meditation and peace etc.) leads to strength in the Force. One's midichlorian count is far from a glass ceiling - it counts for little. Your also confusing the words 'sensitivity' and 'sense', having strong force sensitivity does not ensure a strong force sense. Growing more powerful in the Force improves ones force sense among other things, it is not an entirely inherent ability.
And concerning periods of peace, I'm not sure, I was searching for how long and I chanced upon something that said '2000 years' but whatever. It was a long time.
Some things that need to be corrected however:
What you say about Ataru is a somewhat baseless assumption, Jedi realise the deficiency it that form and it was rarely used alone. Forms such as Soresu, Shii-Cho, Shien and Niman were favored just as much, if not more.
What's more a skilled wielder (and as you said they would be skilled given the flourishing of tutelage during peaceful periods) of Soresu is perfectly capable of taking on a lightsaber wielding opponent e.g. Darth Zannah was trained in Soresu and used in proficiently against several powerful Jedi Masters and defeat Bane himself. And Obi-Wan himself took up Soresu to better counter lightsaber wielding opponents after witnessing the death of his Master. And given that the majority of threats at the time would come from blaster wielding opponents at that time I suspect their were many masters, and as we know, a master of Soresu is invincible.
Your also extremely misinformed concerning the OR period. Mical was not refused training because of the First Jedi Purge, but because of the Mandalorian Wars due to the large number of Jedi that left the order in that time period. In fact I'd go as far to say that the Revanchists were not Jedi, and so using them as an example is a moot point. Considering that they were practically Sith by the end of the Mandalorian Wars, I'd say that is a valid point to make. Counter-intuitively the very Jedi you refer to gaining experience during the war from Sith, were the Sith themselves! May I also stress that it was during the course of the Mandalorian Wars up to (not after) the First Jedi Purge almost all members of the Jedi Order were either dead, or had left. Only 100 remained - likely historians, consulars and the last of the Jedi Councils (who you yourself admitted were weak). That leaves noone to pass on teachings, and lets face it during that time they had more important things to worry about than training padawans. The First Jedi Purge wasn't really much of purge, because all the Jedi were already dead! A expect few, if any, new Jedi were trained until Meetra. So yeah, basically no combat experience was passed on - making that point moot.
Indeed the reason the Jedi managed to rebuild and grow strong was because they experienced 300 years of peace by which they could grow closer to the force, perfect teachings, and focus on study rather than become unbalanced by war. Times that by 3 and you've got the most powerful Jedi Order to ever exist. Let's also remember that that Order had no battle experience whatsoever, against the Sith. In fact they were in a similar position to the Jedi Order of the PT, believing the Sith to be extinct but still preparing for a possible war. As Malgus remarks:
"For 300 years we prepared, we grew stronger. While you rested in your cradle of power, believing your people were safe and protected...but you were deceived."
The Jedi Order of the Great Galactic War seem a lot more powerful than that of the Jedi Civil War, and I believe this is because of the period of peace they experienced. Not the period of war, that only weakened them. Take Satele Shan and her master - despite having no experience in war they went head to head with some of the most powerful Sith of the Sith Empire, Darth Malgus and Vindican. And Darach alone managed to dispatch Vindican. Pretty impressive for Jedi with no combat experience. Imagine that power times three and you have the PT Jedi Order, do you not?
And yes during the Great Galactic War some Jedi would have survived, but the key word there is some. Many would have been killed, that leaves less Jedi to train future generations, which means many Padawans would have received inadequate training. Its a question of numbers and you cannot argue against the fact that war depletes the numbers of Jedi, in particular the number of Jedi Guardians and Knights - these empty spaces are instead filled with consulars, and so future generations become less skilled in lightsaber combat in the immediate aftermath of war.