I don't see what the problem would be giving them a powersword, all considering the fact that the Moritat package gives you a monosword at character creation. Besides, according to the fluff, the powersword defines the IG officer's image. That's not to say of course that the cultural background of the Regiment he/she hails from doesn't affect what they use, but for most of what I've seen it's usuallly as follows:
Confessors: Evisarators
Commissars: Bolt guns and Chainswords
Officers: Powerswords