John Strunk has a vine maple bow that is totally stained in charcoal and it looks pretty sweet. He just pulled some from a camp fire, mixed it with some water and rubbed it directly into the wood.
If you want a "burned look", why not just take some charred wood and rub it in for a cool burnt/camo look? You could cover the whole bow of just take a chunk and use it like a fat piece of chalk.
If you try something cool and new, please share with us OK?
Good luck!