I don't think I've seen this sword anywhere else. Is there a way to find out what it is, even if it isn't a weapon that is obtainable by players?
I don't think there is an exact match - however for a very close alternative, you can look at:
Beheading Blade: https://classic.wowhead.com/item=15253/beheading-blade
or Battlefield Destroyer: https://classic.wowhead.com/item=8199/battlefield-destroyer