Sidestep Charge is a pretty good find, and I agree that it looks like what he's doing, so I'm currently considering putting that in, along with its prerequisite Dodge. Hold the Line (and Combat Reflexes) is another good ingame explaination for how he handles Belkar.

Before I enter Improved [Combat Maneuver] feats, we need to decide something: As I previously mentioned, before my initial stewardship Nale was once shown as having Improved Disarm after this comic, but then a discussion arose about whether whether Rich's portrayal of such maneuvers was proof of their requisite feat, and the conclusion at the time was that not showing an attack of opportunity was not evidence of the feat, so Improved Disarm was removed. If that conclusion is still in effect, we couldn't give Tarquin improved trip here. I've said before it makes sense to revisit our assumptions, so what do you guys think: Should we now assume the disarmee/tripee/graplee not making an AoO means the disarmer/triper/grapler has the Improved [action] feat, or should we continue needing other proof of it?

I am not currently sold on Tarquin being a Tome of Battle class. I agree that thematically it works for him, and he may yet be revealed to be one and I wouldn't be surprised, but I don't think the throw can be used as conclusive proof. Complete Warrior has a class that is all about throwing things, and even in core this could be a creative use of Improved Grapple and abusing the throw-at-a-square rules that Throwing a Splash Weapon provides.

As an aside, I'm rather enjoying Tarquin's style. He's all about the counterattack and it works for him. Good job!