Tasheron's Bow is real neat without the arrows.....but....I preferred the mana bow (+4 and magic resistance) or the strong arm (+2 and +3 thac0 and +3 damage (you'll need some strenght though)). The heartseeker is pretty good as well.

erm ok genie quest, slight problem, I am playing evil at the moment and cheerfully slaughtered the genies to get that bottle that releases an efreet once a day (whoops is my face red etc.) does this now mean I can't get the bow?

I don't know, but go talk to guildmistress Busya and see if she thinks the town's problems are over. If so, then the merchants should start restocking.