Quote from tbl
It's an anime and light novel series, but Kazuma from Kaze no Stigma is exactly what you are looking for. He's always cool and confident and can definitely back that attitude up and then some (he fights a lot of the time with his hands in his pockets).
In episode 20 he snaps and goes on a rampage, while still being totally cool but angry and merciless at the same time
Dont reccomend this actually, besides the main character, it's filled with stupid shonen cliches. The female lead is a tsundere who's personality is EXACTLY like Chidori from FMP. The action sequences are rather interesting, but not OMG blow my mind amazing.