That's exactly the problem with Covenants. Some classes have really distinct and well-functioning abilities that fit into their toolkit. Several others don't and you're questioning why you'd even use that skill at all, especially when it's rotation-breaking like with Shadow Priest or semi-useful like Monk (I love Monk's Faeline ability, but what the heck is the use of this? Monks already have to press a lot of skills and where does this visually beautiful but gameplay-wise mediocre skill fit into?).