Acutally I want to paint like fire....XD||| U see it like glass or sth...isn't it because of the angles? I paint it with a dark colour and make it looks tough (that s why it doesnt look like a normal frame OTZ||||
I think a lot of it is the darker color: it doesn't look like it is giving off light like normal flames. A couple of reference pics I found might give some insight, although flaming weapons are hard to do in real life:
Notice how in all of these images, the weapon is giving off light. I know you wanted to make them appear tough, but if the flames are dark, they no longer appear to be flames, in my opinion. I hope this helps.
However, I still think the piece is really good. Just because the fire looked different doesn't change that. The coloring is lovely, and your linework is clean without being uncomfortably edgy.