Reinforcement

Xiphaem manipulation of blood while still within the body. Works best when the reinforced body part is stationary. Synchronizing to muscle contractions in order to reinforce movement is very difficult and consequently rarely seen: move faster than possible and one causes internal damage. One may reinforce their wrist and hand when striking to essentially create an internal handwrap, but to reinforce the rest of the arm while in motion takes significantly more skill.
Generally speaking, reinforcement doesn't increase speed so much as it reduces how much one can be slowed: top speed remains the same, but obstructions such as added mass are less impactful. This essentially makes it the exact opposite of flickering , which is pure speed.
Reinforcement must be kept brief, generally held for less than a second during a strike, as the act prevents blood from diffusing oxygen.

Resisting Force

Reinforcement vaguely follows Hard Light physics, acting as a self-Phantom Adamantine Effect. Because of this, not only does it reinforce the body in the conventional sense, it also adds an degree of 'fixing' the body in space. It's theoretically possible to use this to delay falling, for example- though not to fly, given that there's no leverage to generate force once in the air.