There is nothing wrong with using filters so long as you use them tastefully. The problem is that most people don't.
It is a given that the lens flare should never be used if you want to be taken seriously. Other effects can make the picture look just as filter raped if taken too far. Adobe may as well have put flashing lights on the filter buttons as far as I'm concerned.
I use filters on my work, usually. Not always filters, per se, but sometimes a color adjustment here, a curves tweak there, and a texture somewhere else. Like I've said, there's nothing wrong with it, but just use them at your own discretion.
Anyways, the picture is pretty good. There are some anatomical problems, as Moon_Lunatic has pointed out. The inkwork is alright, but could be improved. I don't know enough about inking to tell you how to go about that, however.
The flames aren't convincing, really. I understand your troubles, as I've always had great difficulty painting realistc flames when I was starting out. A simple thing is that you shouldn't be attempting to make them on a white background. In fact, don't ever color on a white background. I know you see a lot them around in the professionals' work, but they know what they are doing, what the white does to their eyes, and how to compensate for it. When you've been coloring and painting for long enough, you probably will too.
Start with a dark, neutral color. In addition to not distorting your color perception, the dark back color allows you to emphasize and more properly convey highlights, light sources, and other special effects. With white, your brain can't properly comprehend what's going on very easily, as there isn't really such a thing as pure white in nature.
Anyways, I had a couple of minutes, so I made a couple of flames for your blade. These are just quickies; about 5 min each, but they show two possible variations on the flame theme, and the mood they convey. As is common sense, you will note the flames are most intense where the flames originate from.
