Riastradh, Geasa and other Celtic Religious Powers / Prohibitions

[strayshift]

Reading the Tain, Cu Chullain has several powers (especially his 'warp-spasm' or Riastradh) and prohibitions (Geasa) which shape his actions and his ultimate fate (don't give the Druid your spear!)

It occurs to me these things are ultimately more than just an issue of honour but the interface between honour and divine power.

Put simply: How do people think these things would be best recreated in Pathfinder?

[Detect Magic]

Either monstrous physique or rage powers (beast and chaos totems) for the "warp-spasms". Bestow curse and/or geas for the prohibitions.