Try to get the Annihilator from the 2nd Wight Boss in the Warmaker’s Dungeon, that’s the best 2H Sword at the moment.
If Siptah, you can find Mastodont’s Killer by killing the Yellow Wights near the Tower, very low drop chance though iirc.

An alternative is Baal-Pteor’s Razor, but you need your Thrall to have Agility stats and buffs instead of Strength for this one :+1: