Nightmares of the Last War
Obsidian acidic greatsword
1damage +1d6 acid damage.
This long shard of obsidian has been masterfully fashioned into a large sword, albeit one too large for any medium sized creature to wield. The sword has been enchanted to release an acidic substance with each strike.
The last wielder of the blade was the leader of the blackscale lizardfolk who utilized his massive strength to good effect with this weapon. This sword was the weapon that killed Zanros Dawntracker