since almost all classes have a signet to run (25% increase in movement speed) or some sort of combo to have permanent swiftness you could not do the signet of inspiration of the mesmer always give swiftness out of combat?
For the might boon I thought it would not be bad if it would increase the healing power of 35 also seen that already a secondary stat increases as the damage condition, and could bring some variety and balance to build marked on dps