It's a pretty simple idea really, and would just give the Skill more diversity for element builds and the Convention of Elements ring.
3 of the runes are physical, 1 fire and 1 cold.
Healing rune, for whatever reason, isn't holy. It should be
Resource regen rune, since it can't really be holy now, should be lightning. This is the next best fit for the effect in my opinion.
Boom, you now have 5 different element runes and my OCD is satisfied.