Gloomwater Harpoon seems really bad.
 

Even the Damage Calculators seem to concur that it's vastly inferior to Polished Steel Dirk and EBW. Why is it so popular?

9

basically the next highest bs is a raid drop and also shamans be like I got nothing that is my epic and this is HP and a pointy so it make me feel like it is 1 so there is added interest Id wager.

9/31
STR: +4
HP: +25

That's a pretty nice item in classic.

This^

It’s pretty slow in the main hand, but it does have the highest Pre-planar/dragons backstab potential. Overall, PSD in the main hand might be better if/when you can get EBW. Gloom/PSD is pretty sick on my little 17 rogue so far.

Offhand though? Smoldering brand all fucking day in the offhand once it’s out on Green. Almost a .41 ratio and +3 STR. Godly.

I'd say go for PSD. At lvl ~35-37, with a shaman and bard in the group, I hit 198 with the Backstab