You make good points, but you do not fully take into account the damaging effects that war has on a Jedi Order and there abilities in combat. And it does effect there combat skills, like I said war encourages powerful emotions such as anger and hate, and it also clouds vision and makes it difficult for a Jedi to focus himself. For a light sided Jedi this harms he connection to the Force, unbalances him, and so negatively effects his ability to wield a lightsaber.
What's more, the Jedi would not have received 'excellent instruction'. Yes there are plenty of experienced, battle hardened lightsaber masters out there, but that's just it - their out there, on the frontlines fighting the Sith, where they're prowess in battle and skills with the lightsaber are needed. They don't have the time to train padawans and pass down their skills, because their too busy fighting a war, or worse, their dead.
Think how many Jedi must have been killed during the Great Galactic War, the Great Sith War, the Mandalorian Wars, the Jedi Civil War, and the First Jedi Purge. Most of them would have been Knights, not Consulars. Thousands of teachers lost, and their teachings with them. But surely they can simply learn from the great holocrons? No, at least not in the period of the Old Republic when the Jedi Temple was destroyed and I expect many holocrons with it. We should especially consider the effects of the First Jedi Purge, and entire order was exterminated - Meetra had to start from scratch and that must have had a negative effect on quality of teaching.
We also have to consider that many lightsabers forms had either not been invented until the later Old Republic period or had been invented around the time of the Mandalorian Wars and not yet been refined and honed. What's more a practitioner of Vaapaad would have utterly confused a Jedi of the Old Republic who would have been entirely unfamiliar with it. And concerning what Kreia said, that the Sith Masters of old would were far superior in terms of lightsaber combat than the OR is very demeaning, as few forms had been invented in that period.
- Its actually G-Canon that Windu defeated Sidious in that battle, purely in lightsaber combat however - I'm sure Sidious would have won by applying force lightning, but that's irrelevant as we are looking at lightsaber combat.
- The Jedi Masters I listed were on the Jedi High Council before and during the Mandalorian Wars and the Dark Wars. No they were not warriors, but shouldn't they have been? If were only considering those dedicated warriors of the Jedi Order then your argument falls apart because its clear from this that the number of powerful warriors in the Jedi Order were few if the Jedi High Council lack any distinctive prowess. And Vrook mastered more forms than any of them, so if he's weak then, well...
- The Jedi you refer to are a smattering of exceptional few from a centuries long period that is the Old Republic, I can match that number and triple it just by naming the exceptionally skilled Jedi of the PT era over 3 years. I mean lets just consider for a moment that the PT Order produced some of the most exceptional lightsaber duelists in galactic history - Dooku, Obi-Wan, Anakin, Yoda, Windu, Qui-Gon. Also you base their abilities on their experience in war, but in order to accept that as a point in their favour I would have to accept your original premise, which I do not. What's more the likes of Malak, Revan and Kun only came into their own once they had fallen to the dark side. And Meetra only under the tutelage of Kreia - a Sith Lord. It seems they owe much of their prowess to the dark side.
- While Shii-Cho does have significant draw backs, Kit Fisto nonetheless managed to overcome these and prove formidable in combat. He survived the entirety of the Clone Wars and battled deadly adversaries such as General Grievous whom he would arguably have been able to defeat if Grievous hadn't summoned his magnaguard lackeys, and survived the longest (excluding Windu) against Sidious.
- The Grand Master I spoke of was not 'shot in the back' - he actually moved to arrest Braden (he may have even drawn his lightsaber) and Braden simply buried a rocket in his face - the Grand Master of the Jedi Order, dead in one shot.
- Jaric Kaedan seems to have mastered only one form, which already puts him below most members of the PT Jedi High Council along with several other masters.
- Those Jedi masters on the Jedi Council all mastered several forms and where considered battlemasters of the Jedi Order and many some of the best in Jedi history - look them up on Wookieepedia and you'll see.
- You make good points about Juyo, but lets remember that many Jedi steered clear of it not because they were languishing in peace, but because it drew too close to the dark side. The fact that any Jedi improved and developed it, no matter after how long, is a testament in itself.
- What you said about Cin Drallig is based on speculation. There are other possible reasons for his defeat, the fact that Anakin was the Chosen One and immensely skilled with the lightsaber, and that he had embraced the dark side making him stronger, he likely caught Drallig by suprise and finally - plot armour.
- And concerning Jun Seros, we are talking about the Battlemaster of the Jedi Order whom by your argument, would have become exceptionally more skilled do to experience in war - and yet he was killed by a Bounty Hunter with no hidden strings attached. Perhaps it was Seros' arrogance blinding him that led to his defeat, but that was likely a product of war.
- And I'll admit, there are a lot of other factors concerning Jango Fett.