To be honest, I really do think you should be given something when Withers brings you back as their champion.

I know from a RP standpoint, your character should be proud and thankful for a second chance but, for players like me who think more of the functional reward rather than RP, it just feels lame to get nothing.

I mean it is HEAVILY implied that Withers is the God Jergal, or at least a Avatar of him, so becoming his Champion should give you some sort of boon. In the lore even, Bhaal, bane and Myrkul became Gods by tricking Jergal with a deal, and gaining his powers, so wouldn't Jergal be able to bestow you some form or something?