A question about Sith Lords.

[Lord Revan]

Is it just me or are all Sith Lords apart from Darth Sidious rather limited in what they're powerfull in?

EDIT.what I mean is that they're really powerfull in few things, but medicore in the rest.

[Tiriol]

I wouldn't say so, actually. Darth Tyranus and Darth Traya were both powerful in the Force and able combatants. Darth Vader post-Mustafar was still exceedingly powerful, he just couldn't use Force lightning without frying his delicate life support system. And then there are Sith Lords like Marka Ragnos who are obviously powerful since they managed to rule over an empire of dark side users.

I'd say that the appereance of the lack of power in other Sith Lords comes from the fact that they don't get much mention or "screen time": Sidious and Vader are quite well presented by the multitude of comics and books in which they appear, and the movies of course. But the rest... well, they barely get a mention and an appereance or two.

Take Marka Ragnos for example: he didn't do anything in the Tales of the Jedi except that he died and was buried (and later his spirit influenced Ulic Qel-Droma and Exar Kun to unite their power). And yet he was the Dark Lord of the Sith Empire for a century. His latest appereance was Jedi Knight II: Jedi Academy in which he was a light-sider's boss fight and was kept off-stage until the very last moments (although he did possess someone in a matter of seconds, drained Force energy from Jaden and was not killed along with Tavion). He didn't have much time to show any great and diverse Force powers (and the gameplay didn't actually allow that like the novels and comics would have had).

In short: Sidious (and Vader) gets much attention and thus his powers are described in greater detail and he has the on-stage time to show more powers than the other Sith Lords.