Hey RedSuinit. Here is my edit and advice on how you should proceed.
As Yukie mentioned earlier your dude has gorilla-arms-disease (which seems to be a common problem). I've drastically raised his elbows. Anatomically, they usually fall right above the love handles or higher. I also gave him longer shins, because they were so incredibly short.
As far as posing, I raised his left arm, because with both hands down by his waist it seems more like he's doing a naughty dance, or getting read to roll some dice, neither of which makes me think he's ready for a fight.
As far as blandness, I gave him to stripes on his shoulder just to add something, a belt and buckle, because bad dudes wear belts and it helps break up the torso from the pelvis. As well I slightly hinted at pockets on the jeans. You'll notice also that I gave a ring for his neck. Before it seemed king of like he wore his shirt on backward so it was riding up his neck. I also varied his jaw a bit so it's more manly and tough guy like. Before it was too soft and pudgy.
Last piece of advice, especially since you're new to pixel art (not sure if you're new to art in general): on complicated pieces like this, you should really fine tune the anatomy of your character, style and costume, and especially the pose, before starting to animate. It will cut down on development time when you have to make a correction and then go through every frame and correct it (this is only 5 frames so it's not as big a deal as it could be). So in short, put up a still picture of your character, get critiqued on that, then once you're satisfied, move on to animating.
Okay, one last piece of advice: if you think something looks wrong with your picture, flip it horizontally (meaning if he's looking to his left, flip it so he's look to his right). Almost immediately, you'll notice what's wrong. If you don't, then flip it vertically so he's standing on his head. If you still don't notice what's wrong then post so you can get some C + C.
This time I mean it, last thing: honestly, my edit can be pushed much, much further. He still kind of looks like he's just standing there, maybe looking at his invisible phone. Bring up both of the arms even further, so they're actually almost chin height and he'll look ready to punch someone's face off.
