Well... That escalated quickly.
First off, I feel I should apologize. When this whole thing started I made some assumptions about the writer based on what I'd seen of the character (namely that you'd done RP combat before and had an idea of general etiquette), and for that I'm sorry. I shouldn't have let an assumption like that color the way I approached the issue. A veteran throwing the etiquette to the wind is a completely different scenario than a newcomer just not knowing how things are usually done.
Secondly, a clarification. The only reason I was objecting to most of the things Herriman did was because you consistently had him trying to match Mifune's speed, when he already had (off the top of my head) more than half a dozen other ways to approach the situation that wouldn't require him to become as fast as a purely speed based character. Herriman doesn't need to be anywhere near as fast as Mifune in order to beat him, so when you kept consistently trying to add the advantage of speed to all the other advantages Herriman has (and could use to great effect), it started to tick me off. Maybe you just didn't see the potential in all his other abilities, but when a character who already matches or exceeds his opponent in power uses a move (that wasn't in the approved CS) that makes his weakest ability just as good as the opponents strongest ability, without any drawbacks whatsoever, I tend to cry foul.
Thirdly, If this is your first foray into the arena it is admirable that you picked up so quickly on the mechanics of charging an ability (though for future reference, there should be at least some small hint that the charge is continuing in each consecutive post, and the rules for combining charging and other attacks tend to vary from GM to GM, so that would be something to bring up with Light), and that you balance (most of) his magic and mutation abilities so well in spite of the lack of limitations in the CS. It's just that in an arena setting, more often than not if your opponent CAN do something, they WILL do that thing when backed into a corner, even if it's something they originally would have considered overpowered. Maybe we're all just cynical around here, but in a competitive environment the benefit of the doubt tends to get abused, so we're all a little hesitant to give it.
Fourth, I think the reason you feel you're having so much trouble against Mifune is that you're trying to match his strengths instead of capitalizing on your own. If you keep trying to out-speed him, you WILL lose. Speed is his thing. It's what he's best at, and trying to match it in addition to all Herriman's other abilities is pretty much the very definition of powergaming, but you don't need to even come close to matching it in order to beat him.
Fifth (and this one's for Drall), Dag does have a point about how you avoided his attack. If you're in midair, you don't have the leverage you'd need to alter your trajectory like that (at the very least, you'd have slammed into Herriman's chest), or spin around to attack like you did. After everything we've been going through, you should know better than that. However, since the attack itself was of a PGing nature, my advice to both of you is to just take things where they stand and move on (unless you both want to edit both posts).
And the sixth and final point, I like the new description of the magical abilities. One thing to keep in mind though is that because he's a jack of all trades, he shouldn't be able to match the capabilities of someone who's a specialist in a particular area. Krix, for instance, specializes in fire and earth manipulation, so he should be able to create a hotter fireball than what Herriman could summon, and Mifune should be able to move much faster (since he is even more specialized with just speed) than Herriman using a speed-enhancing aura. This isn't something that needs to be added to the CS (unless Light says otherwise, but I doubt he will), but just keep it in mind when you're trying to go toe to toe with another character's specialization. Since Herriman is very much a jack of all trades, more often than not he'll end up the loser in that kind of contest. The way you make up for it though is his sheer adaptability. He's the kind of character that forces you to out-think, out-maneuver, or out-wit your opponent instead of straight up overpowering them (unless they do something stupid like Priroda's suicide charge).
P.S. I don't think you should get rid of the teleporting. It makes sense due to the god he serves, and all it needs to avoid being overpowered is a couple limits. For instance, if you removed his ability to see this world while he's phased out (so he's just as blind to the world as the world is to him), and his ability to carry momentum over through the shift (and it was understood that he couldn't ever phase one solid object inside another), I think it would be fine in the context of this RP.
Disclaimer: Everything in this post regarding what is and isn't allowed in this RP is contingent upon Light agreeing with it. :P