I'm total newbie here perhaps, but receiving ===OBLI=== by normal strikes from anyone wearing divine weapon, and >>>ANNI<<< by any paladin's wrath leaves no single chance for a duergar thief.
Faceless Empire characters (with an exception of Valryn and few others) make RP kinda boring as well.

Good luck, huh.

Duergars get toasted by wrath very easily. As well as light and divine based attacks. Even the experienced players get toasted by wrath spamming paladins and deathblow strikes. As a thief you must utilise your stealth to full advantage. Jack the enemy, recite some scrolls, or just run, wait and watch for your chance to strike. I believe a duergar thief has it better than a duergar warrior.
Anyway I briefly interacted with you both before you were oathed and after when we fought. You put up a good fight in the plains there and if you continue with more of the same you ought to be throwing us mean duergar thieves in no time.
Good luck, see you in the fields.

Keeping working at it. Your next will be even better.