Since I don't like the rework of mantras and tomes of anet so I gave up on open world firebrand (a while ago already) and took willbender instead. And I must say it doesn't disappoint me, I'm still using it until now: http://gw2skills.net/editor/?PWwAw+tlVUxSqaYhtu6WbnW0WbxMA-DyIY1o7vMyrqKMRd4QQBCR3/Z6RQFA-e
Well, some people might think it's weird what I have take in gear and ultys, but I did it intentionelly for my purpose, for example so that I don't have to rely on the portable united legions waystation for breaking defiance bars.
And for encounters where I need even more sustain and defence, I just change radiance with valor: http://gw2skills.net/editor/?PWwAw+tlVUxSqaYhtu6WbneyWbxMA-DyIY1o7vMyrqKMRd4QQBCR3/Z6RQFA-e
I mean depending on your taste honor would be possible too instead of valor.