Were there any female klingons amongst the candidates partying in the hall? I cant recall seeing any so if there were female klingons there they must have been few in number.
Maybe the reason they took O'Brien rather than Dax was because being female she was more likely to attract unwanted attention form the many increasingly drunken males intent on showcasing their masculinity. Not that she wouldnt have been able to handle it but it would have made setting up the relays unnoticed quite difficult.
On the other hand, she could be used as a distraction, if she was kept on the other side of the room, to keep everyone from looking where the Relays were being placed
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?