Hmm...might be interesting. Or perhaps if you use it against a Justicar it is revealed to everyone? That could be fun.
As for Healing vs Defense, it sounds like I need to explain the difference a bit clearer.
In combat, there is an Attack roll and a defense roll. The base damage dealt is Attack - Defense (minimum of 0).
After the base is determined you account for Affinity. Double for cross affinity and half for the same. Once that is done, we subtract Healing and you take whatever damage is left over. Whether defense or healing is better depends on what happened with the affinities.
Example:
Total 14 attack, 10 defense, and 2 healing.
If the Attack is Earth and Affinity is Water, you get 14-10 = 4, X1=4, -2 = 2 points of damage. If he'd had two more points of defense instead of healing, this would be 14-12=2, X1=2 -0 = 2 points of damage. Defense and Healing are equivalent for neutral attacks.
If the Attack is Fire and Affinity is Water, you get 14-10=4, x2=8 -2 = 6. If he'd had two more points of defense instead of healing, this would be 14-12=2, X2=4 -0 = 4 points of damage. Defense is better for cross-affinity hits
If the Attack is Water and Affinity is Water, you get 14-10=4, x.5=2 -2 = 0. If he'd had two more points of defense instead of healing, this would be 14-12=2, X.5=1 -0 = 1 point of damage. Defense is worse for same-affinity hits.
Make more sense now?