The only noteworthy drop I remember getting on the last mission was the Bloodletter sword during the Chaos campaign. But the Fist of Gork isn't even that good, I only use the Kutlass.
Oh, there was two separate ones? Can't say I noticed that. I may have obtained both, but I didn't even look at them enough to be sure.
Come on there's no way it would *only* drop during the last mission. Everything is random, I've got items as random drops that I already had from a mission reward, the second time I did the Chaos campaign I found the Hellblade before the last mission (and I was pretty disapointed with it). Just farm the first Wraithlord during the last mission against Eldar, he always drops stuff, you'll find the Fist in no time.
Exactly. In this case, you can just start the mission, go kill that Wraithlord (shouldn't take too long), pick up its drop, stop the mission and go back to the start map, start it again, kill the Wraithlord again, etc until you feel like you have enough stuff for the final missions.