Just to clarify, you have to keep the feet equipped to get the reduced TP cost during Meikyo Shisui. If you switch feet then weapon skills still cost 100 TP.
Regen potency is 7/tick for Regen (+2), 15/tick for Regen II (+3), 25/tick for Regen III (+5), 37/tick for Regen IV (+7). So an improvement over NQ/+1.
Edit: Enhances Protectra V effect on +2 feet gives an extra +2 defence per merit. Lame!