When either playing as or against Geiger, it is important to know when he is charged. The gear icon provides good feedback to the players, but unless you keep your eyes focused on it, I feel like it isn’t terribly useful in actual gameplay.
I would recommend to add a (more) noticable flash effect on the gear so that you can notice it out of the corner of your eye rather than having to look directly at it. Even better might be some sort of indicator on Geiger himself, but I can’t come up with any good idea for what that might look like.