Well, if you have attonement on yourself, you get the healing through it, so it mitigate SWD backlash on that amount, which is not bad actually. What's also important is CD reduction. In PvP, we will use SW
as a way to break CCs like polymorph, repetence, etc. Reducing CD on the ability means you can use it more often to avoid being CCed. It is useful, but not that gamebreaking I would say.
This one is interesting, you can also use it as a way to escape when you're trained by melees. If you go Venthyr (which seem to be superior priest pvp covenant now), you will have also teleport ability, which actually gives us some movement, a thing we were always bad at. My priest is a void elf, so when I combine my racial, covenant ability and possibly this legendary, it may lead into movements unexpected from a priest. Not bad I believe.