Honestly, I find some of the regular enemies in there harder than the bosses (especially those of the drake kind....). With the right tactic, and if your levels are very high, Trema isn't much of a problem, apart from the fact that it's long fight. Don't remember much about Paragon, though (it's been almost two years I haven't played that part of the game), but I think it's pretty much the same difficulty level as Trema. They are definitely a lot harder than the first bosses, though, so be on your guard