Definitely a lil undertuned for laners.
IDK. It's either a stat stick keystone. Or it can heal you late game which is kinda interesting. The problem though if the healing is introduced earlier it's simply more directly competing with grasp in a less interactive way.
TBH I'm not sure if resolve has ummm. Engaging keystones beside grasp. Certainly not so much weak but more like... flat and uninteresting..? We have things like thunderlords and dft, stormraiders or grasp having visual impact and fantasy. But other two resolve keystones are just there. Invisibly granting tankiness.
I think it's good we have one keystone for bonus hp to improve desire to build resistance (it's not good optimally it's limited to junglers however). The other is flat damage reduction. Perhaps that could be better if it was retargeted as a armor/mr keystone to improve its desire to tanks who prefer HP in their buildpaths.
Bond of stone as a support keystone is doing nothing to me to fulfill a "fantasy." Its damage transfer is negligibly small and invisible to provide satisfaction that way.
I'll try my creative hand at a mastery to replace bond of stone: your champion's skin gradually turns to smooth iron as he receives champion damage [making them look like iron mario], increasingly higher armor/mr bonus as stacks are given: fervor of iron ( horrible name lul, came out with the fantasy before the name or thinking of fervor of battle)
As a gnar main I find none of the resolve keystones super great. But grasp works okay especially since he is resourceless.