Honestly, i think we have enough stuff tied to block...

I'd instead have it be an effect of Royal Authority...reduce cast time by 1-1.5 S on the next spell cast.

Has the benefit of letting us be a little bit more of an offhealer while we're offtanking (Making up for our lower DPS in general), gives our DPS Combo a "thing" like pretty much most other combos in the game, and it paves the way for future spells in the paladin kit. Long cast times that we reduce with the combo, giving us a unique casting style all our own.