Oh there's no generator on them? You should probably give them one. There are a number of reasons for this: for one, blaster powerup does 2 damage and has infinite ammo, while ice will only do 1 damage (the powerup just increases its range). So, whoever gets the blaster is at an advantage.

But secondly, non-regenerating powerups don't really work when considering how most people play. Usually people start off games by collecting all the powerups and then returning to the bases, before the countdown begins. I don't know why people do this (I prefer to just start off normally), but this won't really work with nonregenerating powerups - the players will start unevenly, when the idea is for both of them to be equal.