If I understand correctly it is supposed to be the carrier of masss. At the same time its proposed mass is larger then the mass of a proton or electron. How can mass not be quantized to multiples of the value of a single higgs boson?
90-99% of the mass in regular matter is due to strong force interactions. In things like protons, neutrons etc the Higgs is only responsible for a small amount. See [1] for a little more detail.
As a quick aside, gravitons aren't quite kosher science yet. We haven't observed them, and we don't even have a coherent theory of how they would work. Something to do with equations being non-renormalizable, I don't claim to understand any of it.
1: http://www.reddit.com/r/askscience/comments/pd6wc/why_is_the...