Herriman saw Mifune begin to pick up speed in order to keep his sword in his hands, and smiled internally. He couldn't smile externally, since he'd lost that ability with his humanity. The chain link was still locked tightly around Mifune's blade, so Mifune would have even less control than he thought he could ever posess. The sound of tendons and muscles tightening signaled something else, and the chain started to build tension at the base, the arm that served as the flail bulging as the muscles rearranged themselves to make way for the tension being built. 

As Mifune drew closer, Herriman swung the arm attached to Mifune's sword by the chain off to the side at a dramatic and extreme angle, the chain practically explosively detaching as it rocketed off to the side. If having a fifteen foot chain of mutated bone and chitn (which was the exact opposite of light) attached to your blade was bad enough, now that heavy chain was flying off to the side at breakneck speed. If Mifune would try to correct his blade's course, the chain would reverberate backwards towards him, striking him in the back at worst, or throwing off his aim in the other direction at best. Given the massive speeds at which Mifune was traveling, it would no doubt be difficult to correct his blade, since it would become a flat surface against all that wind resistance.

To take advantage of this no doubt unexpected ruination of his aim, Herriman merely turned his body so Mifune's blade (if it even hit) would strike at a 45 degree angle, enough to glance off of the extra protection he had placed there. To combine this angling of his body, Herriman also held out Setrak point-first once he was sure Mifune's velocity was irreversible, and waited.