Why is shield swipe so bad?

[Gilthas]

If I'm tanking a boss and am way ahead in aggro generation, I'd rather start stoneskinning and using Riot Blade, myself, than use Shield Swipe. If Shield Swipe gave some sort of buff, perhaps a 10% defense increase for 10 seconds or something, it'd become worth using.

I'd argue against making Shield Swipe give a good buff without how the ability is activated being redesigned. Give it a good buff and PLDs could probably have it up indefinitely by using a shield with a high block rate. That's why it currently makes sense to have the ability cause a status effect that a mob can build resistance to.