Last Stand IS a viable option for a weaponskill, BUT it's so situational that I eventually scrapped it and went for H2H instead.
I really enjoyed spamming last stand on the eye mob in konschat [A] that takes no damage from melee. TP on the adds then WS the boss, or just tp with /ra on the boss. I only ever used it with xbow though, so damage would have been much greater with a gun, but I wasn't going to carry stacks of cannon shells around with me, and only 7 Handgonnes and 0 +1s have sold on AH so far on Phoenix.
1 fix that would REALLY help, is simply allowing Cannon shells to stack to 99 and/or be pouchable.