Did some testing to see how much an additional +100 healing power would affect healing. All this testing was done with a base healing power of 300 (from Honor trait)
Before:
Virtue of resolve – 104
Superior Sigil of blood – 493
Trait Altruistic Healing – 73
Gains from an additional +100 healing power:
Virtue of Resolve – 6 points
Superior Sigil of blood – 10 points
Trait Altruistic Healing – 1 point
To increase heals 10% you would have to increase healing power by:
Virtue + 173 Healing Power
Superior Sigil of Bood + 493 Healing Power
Trait Altruistic Healing +730 Healing Power
Still have more testing to do.