Haidate with the crit. damage augment more than likely pulls ahead of N.Legs. Particularly in Abyss.Heca Subby is a nice piece, no doubt. It really comes down to whether you see more benefit from Att +22, DEX +9, or the flat +15 DEX boost from Byakko’s Haidate.
Also, I'd opt for Flame sachet over the smart Grenade or even one of the new grips... which i forget the stats of.
I'd also suggest Temperance Torque or Ire Torque(+1) over Ziel Charm. Ire Torque you have to worry about accuracy with the NQ, but not with the HQ. Besides, if you're packing Twilight helm, Anguinus belt and Haidate, you're more than making up the accuracy loss.
Also augmented my heca mitts today with:
2 STR
2 Axe Skill
Crit Dmg. +2