I can now personally confirm that- despite Wowhead's claims- the Horseman's Sinister Slicer CAN drop for both hunters and warriors.
\*Disclaimer: The *comments* on Wowhead do mention that is has dropped for hunters, pallys, warlocks, priests, mages, druids, monks-
*realizes one of the comments specifically calls out fury warrior (my own spec), which I'd missed before*
-... as well as death knights.
While yes, said list of comments (not to mention one that states it should drop for all classes) SHOULD have put me at ease earlier, I've been burned before so aside from just wanting my own army of squashlings I had to check. Don't forget to talk to the statues on the left as you enter the dungeon and accept all curses for better loots.
Also, not that anyone asked, but the rings he drops are iLvL 32 when dropped for a lvl 20 character, and CAN be socketed. Now I just gotta see what the [Horseman's Horrific Hood](https://www.wowhead.com/item=117355/the-horsemans-horrific-hood?bonus=13827) means when it says "Let the horseman laugh through you".