I wouldn't give the commissar a power fist, BTW - the worst thing you could do is be tempted to use it. Let me explain:
1. When one attaches a commissar to a unit of conscripts, it is generally to help the conscripts "stay in the action."
2. The independent commissar is an independent character, meaning, that in melee:
a) he can only hurt people if he is in base-to-base
b) he can only be hurt if he is in base-to-base
3. If the commissar dies, your squad will run.
Thus, should you get into melee, the LAST thing you want is for your commissar to get into base-to-base - indeed, don't move him in until you are forced to. Giving him a powerfist is not only a waste of points, but actually makes the squad less survivable, as it both makes you more likely to get him inolved in the actual combat, and it makes an even bigger target for the people who do get into contact with him.
Inquisitor Psychologis Ruminahui