With the introduction of Protect V and Shell V at Lv76 and the possibility for a Protectra VI/Shellra VI somewhere between Lv90~99, the Protectra V and Shellra V merits are loosing their effectiveness as merits.
A suggestion that I'd like to make would be to change these merits to instead enhance the effect of the spell type:
Protectra Effect
Increases the defense of party members within the area of effect.
Increase bonus defense by 2.
Shellra Effect
Increase the magic defense of party members within the area of effect.
Increase bonus magic defense by 1.
This would pretty much grant exactly the same effect as it does currently, however it'd boost the effectiveness of all Protectra/Shellra spells instead. Protectra V and Shellra V could then be implemented as magic scrolls for Lv75 or Lv76 (to follow the trend of previous Protectra/Shellra tiers being the same level as their single-target spell).