I thought I remembered someone making a comparison between this game and Severance: Blade of Darkness. I'm talking about the combat system here. Can anyone confirm or deny this?

I have never played Severance, but I can tell you that it is a pretty basic combat system as they go. click right to block, and hammer the left mouse to attack - and from what I have played so far... about the first 6 or 7 missions, that seems to be it.
Level design is pretty basic too, the main thing I can see the game has going for it is the nice graphics for its time. Everything else bears the hallmark of a basic console port.

Short answer, no.
Long answer. Enclave can in some ways be compared to the Severance, good game too btw, but there are no complex combo to keep track of. You basicly have to block and dodge the attacks and then retaliate when the chance presents itself, there are several good guides for the game out there that can tell you what class is ideally suited to what lvl of the campaign youre on, light or dark, but experiment whit them and you might be surprissed at how resiliant some of them actully are.
Also so there not so much blood in Enclave as opposed to Severance where you can really decap foes. But I still recomend you give Enclave a try if you liked Severance. I sitll regulairly find myself looking longing at my old Severance and Enclave CD's, yes Enclve runs fine and my PC, but Severance is on heck of a bustle to get running, but worth it :)
In short, enjoy Enclave and have fun with it.

Well I hope one day the Severance will be released on GoG too.