Looking for this book

I read this a long time ago. More than 10 years ago. (This series was the first I read that didn't have any pictures :D)

It's set in a futuristic universe and the main character(Can't remember any names) is the last of his race. They were a mercenary race, supremely trained. Their planet was destroyed right before him and his squad got back. The rest of his squad died, and he was radiated in such a way that he was slowly dying from that part on(The radiation was in his bones, no other part of his body).

He meets this psychic alien who replaces his bones with a type of metal that is completely indestructible(similar to Wolverine), and the books (there are 4 in the series) chronicle his adventures after that.

If I could just get the name of the series, the writer or even one of the books, I would be very very grateful.