It does seem very low. I'm questioning whether I should take it in the end. It doesn't stack with itself, though it seems to last until you get hit or combat ends. It also seems to need the full 3 hits to even proc the temp hp? It's more about damage mitigation for melee then anything else and from what I understand Astral…
Cool. With 5/5 BF here's what I got for ~1 pip. Lance of Faith - 12 Astral Seals - 8 Sacred Flame - 9 (1.11 pips) Searing Light - 3 (1.16 pips) Blazing Chains - 2 Forgemaster's - 3 (1.16 pips) So it looks like in the end BF will save you about one Encounter ability for the most part to gain a pip.
How many mobs are we talking about to test? I think Sunburst and Searing light both generate Divinity based on the amount of targets you hit. At the very least, trying it out on the 5 packs of Imps in Helms deep, I got a bit over 1 pip after 2 Sunbursts from completely empty. This is with 5/5 BF.