Having such a high skill in Enhancing and being a frontline tank that uses Enhancing/Divine Magic primarily, would Temper not be a great spell to have? Sure RDMs would be a little hurt that one of their exclusive spells is now shared but giving RUN a self-cast Temper isn't the same as SCH getting Phalanx when /RDM and AoEing it. It would help RUN's DPS as a tank and make them more competitive and it totally fits their style. RDM and RUN don't compete for the same party slot anyway so I don't see it really interferring with RDM much.
Could give RUN Temper at level 55, and then give them Temper II(Sabre) at 97. Sabre could either give a higher Double Attack % or a smaller Triple Attack%. Neither would stack since they'd both give 'Multi-Strike' buff. Temper could be a 20% DA, and Sabre/Temper II could be a 10% TA, obviously Temper II/Sabre could be a 3min recast and cost a lot of MP. Additionally could just give RUN the Temper spell and give them a piece of AF2/AF3 armor that enhances the effect and makes it into Triple Attack. A multi strike spell on RUN coupled with Embolden would really make them able to hold hate a lot better.