Although rancor collar obviously eclipses this items use for melee, the addition of the rancor mantle (and the fact that rancor mantle+collar do not stack) allows this item to open some new builds for people who really want to up their crit rate
Would this work for a scholar using shattersoul? I am not sure why people would use this when it is a magic crit hit weapon skill. I am guessing under no means should someone use this to cast magic in.
If you have a high rate of Double Attack / Triple Attack (example: Saber Dance), consider Rancor Mantle + Nefarious Collar as a potential alternative to Atheling Mantle + Rancor Collar.
For multi-hit critical WS, Rancor Mantle + Justiciar's Torque will probably provide better results, however (although for Stringing Pummel / Victory Smite on PUP and Hexa Strike on WHM, Rancor + Nefarious is really the only way to go!).