[Rataxes]

I did beat Imp Ilyich, it isn't that hard for a rouge if you got good stealth skills. Take out the demon with traps, lure out Ilyich and isolate him from his gang. Then just Hit and run, hiding in shadows in between charges. I took out his remaining goons with the aid of the summons the magical acorns provide. A combination of traps and Hold Person spells took care of Rasputin and Kamazarov (can never get that name right), while Zhivago fell quite easily in a straight face to face combat.

The advantages of being able to go invisible at will in the first dungeon are many and great, you can for instance rest without fearing retaliation from the Thief/dog packs, since you can hide and escape from them before they appear.

My Swashbuckler specialized in Katanas and acquired the Celestial Fury to be used together with Belm at lvl 11, it really made the game a lot easier there for a while. I had to exploit a bug that allowed me to exit the 2nd floor to actually beat the Guarded compund though ( the 2nd floor is a quite big place with lots of walls to hide behind, so it should be doable without exploiting that bug I think)
Sanchuudoku replaced CF at lvl 16, and will probably be my end weapon. I've also always kept the Tuigan Bow in my backpack and arrows of dispelling and piercing in my quiver.
I'm not aware of any 1-handed melee weapon other than Belm that adds attacks...