[@Shard]

Thanks for the speedy reply. Answers to your question below.

In regards to power I hadn't really thought that far ahead. If you have a look at my sample post my characters stress over the alarm clock caused his power to make it explode when he touched it to turn off. This is about how far I thought about the power. I am thinking that, because dark matter will go through the process of annihilation, that the explosion isn't a catastrophic type (This would kill him too!) but more a controlled explosion going outward from where it originates on his body. I would think at his PEAK ability maybe blowing a door off its hinges could be possible? He isn't going to be blowing people away just by shaking their hands but maybe cause burns if he loses control when someone shakes his hand too strong maybe. There aren't going to be massive explosions erupting from his hands every time he gets angry or something. 

I would say my final thoughts on it are it is more the force push as the annihilation process doesn't actually involve heat so much as a reverse in pressure. Simply put if he were to put a bunch of the dark matter in his fist and then punch someone the person would be thrown back before his fist hit them. Instead they would be hit with the dark matter which would then annihilate (aka collapsing in on itself causing an explosion and the force of that would throw them backwards.)

Does that answer the question? Since this is a new power I am thinking up I am not completely confident in everything as it is a work in progress.