Some infos before starting:

Kezhou: i4&80lvl&all skills maxed out

Fina: i2&80lvl&all skills 8lvl

Daphne: i1&70lvl&all skills 5lvl

I've tried out both morale/resolve builds on act 10 

this one is resolve kezhou

this is morale kezhou

His resolve build

With my current resolve build, he gains total of 31,38% resolve. Of course this can be higher with high-invested wedges. You'll get more resolve naturally. I'm just showing my current progress with my resolve kezhou.

His morale build

I have +7 prime&morale, but didnt use it to make the comparison fair. And tried to build him and his supports all the same except the resolve/morale.

There aren't really much differences. Both builds can work well, it's just which playstyle suits your taste. If you've already built kezhou without resolve, then you don't really need to build resolve kezhou, just continue to focus on farming your other characters. Seriously, the difference isn't even significant. But sure, if you think you'll have fun, then go ahead.

Honestly, this resolve build is fun to play but i'll continue to stick with his morale build because the resolve thing simply doesn't suit my taste.