I would agree with the numbers being too high. The idea I had was to make it soak a big hit or two. Maybe a better way of doing it would be to increase the heal and decrease the absorb amount. It should probably be lower than SAC, something like:
Instant 45 second recharge
Protects the target with an earthen shield, causing attacks to deal 15% reduced damage and to heal the shielded target for (500% of Spell power). 3 charges.
Instant 1.5 min cooldown
Reduces damage by 50% from the next 3 attacks that damage you for 15% or more of your maximum health.
Hand of Sacrifice
7% of base mana 40 yd range
Instant 1.5 min recharge
Places a Hand on a party or raid member, transferring 30% of damage taken to the Paladin for 12 sec or until the Paladin has transferred 100% of their maximum health. Players may only have one Hand on them per Paladin at any one time.
40 yd range
Instant 1 min cooldown
The target’s skin becomes as tough as Ironwood, reducing all damage taken by 20%. Lasts 12 sec.
Your Ironbark also increases the healing the target receives from your periodic healing spells by 20%.