I am not suggesting Xizor's assassins confront him. Battling Revan = no-no. But blowing up his ship and/or sabotauging the systems for an easy death in space battle is another matter entirely.
How exactly would they get on his ships? Bribing a guy that is fanatically loyal to someone is rather unlikely...
Since when do IG series droids "run around"? They are skilled assassin droids, they will have no problem employing Xizor's tech and intel to find Revan's ship.
IG series droids aren't exactly subtle, that's my point, not denying they would have no trouble locating Revan, their problem is they are less subtle than a bunch of rampaging HK-50 droids.
Okay, on this HK argument.
1.) Where does he get these parts? The Black Market? Good luck, the Black Sun kinda controls that.
2.) So..... instead of leading an army, Revan sits in his room all day building a droid?
3.) It would be a prototype with no combat experience.
How did he build HK-47 then? Seriously, Revan could simply build another HK droid as a hobby of his on the side, he found time to put together HK-47, and HK-47 wasn't exactly a novice in combat... We're talking about a droid here, Black Sun may control a lot, but they don't control everything, and I suspect that the HK series actually used military equipment components for the most part, cause HK-47 was supposedly constructed while Revan was leading a military force, he wouldn't have been able to hunt down underworld components to construct HK-47.
Xizor doesn't need to win a war. He needs to win a battle. By throwing all his forces at Revan's flagship with a gravity well to seal the deal, this debate comes down to one battle. And tactics won't save Revan from the wrath of the underworld. They have tactics of their own: hit-and-run, ambushing, etc.
One of Xizor's prize "admirals" had trouble against 2 freighters and 12 X-Wings, even with the fact they were facing Rogue Squadron, there is no excuse for having that much trouble even before the Imperials joined in the fray.
I'm pretty sure loyalty doesn't protect people from assassins...
Depends, the assassins Xizor would be hiring would generally be in it for the money, to be blunt you don't get paid if you're dead. So there are risks these assassins would not take, that a fanatic would take, and thus Xizor's assassins might not be as dangerous as many assassins that Revan already had to face.
Translations: Xizor's assassins would not resort to suicide tactics, because they wouldn't collect their money if they died, they wouldn't be willing to lose their life in an attempt to take out their target.