I decided I would copy paste something I typed out on reddit. It seems like a good time to do so.

This is the origin of all the healer cross class skills:
WHM- 3 (Cleric Stance*, Protect*,Divine Seal/Largesse*)
AST/WHM- 1 (Shroud/Luminous Aether/Lucid Dreaming*)
SCH- 1 (Eye for an Eye*)
Other/new- 4 (Break, Swiftcast*, Surecast*, Rescue)
All- 1 (Esuna*)

*Required for current WHM functionality.

I should point out, that my other 3 personal (midcore-ish) cross class skills were Virus, Blizzard 2 , and Surecast. However, I never used any of these, nor did I have them on my hotbar. Please don't scold me for not using Virus. I know I'm bad. ;~;