Maybe I just missed it when it happened, but I just noticed it today as I was working on getting HealCalc back online (it's coming soon(tm)!), but it seems that Spirit Shell has received two key quality of life improvements at some point, so I thought I should mention them here in case others like me completely missed them.
1. Single Target Heals cast under Spirit Shell now add stacks of Grace. Also all Spirit Shell amounts still benefit from Grace.
2. Spirit Shell amount is affected by the Archangel buff.
I'm pretty stocked personally. Especially the second change offers some great opportunities for serious pre-shielding.
PW:S on the other hand seems to completely ignore Grace, thought it does respect the Archangel buff. This feels out of sync to me.