@coffee
Been watching this thread a while now and I must say that your edit of the animation in the prior OP update was exactly what I was thinking. For any really strong attack, the attacker would put his entire body into it, thus there would be a lot of anticipation to the animation, and the visual energy buildup really does the trick there, not to mention you improved the sprite's readability and visual appeal with more follow-through on the cape. Nice job.
I did want to mention to the OP (and anyone else interested) that this kind of anticipation doesn't necessarily need a visual representation of the energy buildup as long as the limb charging up the energy moves slightly away (in the opposite direction) from the intended direction of movement before actually moving there. That particular trick is the major key in the buildup of that 'pop' of energy you see in a lot of anime attacks.
Although the key to lively animation is significant 'change' from frame to frame, powerful sudden directional movement mandates this opposing movement to build up (anticipate) the energy required to execute the action.
Someone like PPD, who is known for his very effective animations, has this sense of anticipation down to a science (among the other basic animation things, such as spacing, overlapping action, follow-through, etc., which increase the believability, readability, and dynamism of his animations -- and at a resolution this small, all you really have is effective animation to get your point across!)