PGL and GLA give us some self-preservation abilities since if the healer dies your fight will probably start going downhill. If you use a shield you can use Outmaneuver for increased block rate and Shield bash, both of which are situationally useful. You should get enough TP for shield bash with one swing so it's not a bad idea to have it ready if you're fighting caster enemies, and both are quite nice for soloing when you should be in active mode.