First of all I have to say I LOVE this build. As someone who ran triple meditations and found my self still unhappy with my survivability, I have to say this is awesome.
It feels like Guardian really comes into its own by embracing boons.
It’s SO much more supportive than triple meditation too.
Using virtue of justice, and Sigil of Strength on my weapons gives so much might that I don’t do THAT much less damage with this spec as I did with triple meditations.
That being said I think a very viable option for a more aggressive choice of rune would be superior rune of Hoelbrak/Fire/Strength. You get 25 power instead of 15 vitality, and you get 20% might duration rather than 10% boon duration.