Vivacious Pulse MP recovery from Tenebrae is based on Divine Skill. Not sure exactly what the calculation is.
No gear i wore changed recovery value until i equipped runeist pants. Confirmed by /sch in light arts which resulted in massive boost (my divine is way underleveled

)
So some basic #'s from testing.
100 skill = 40 mp recovered/3 runes
115 skill (runeist legs) = 44 mp recovered/3 runes
385 skill (/sch with runeist legs) = 152 mp recovered/3 runes.
Appears to be roughly 1 mp per 2.5 divine skill.
Food for though if anyone else wants to attempt to confirm #'s.