Stormlight spoilers: question about sons of honor and Gavilar

I'm a little confused about the son's of honor purpose: it seems like their motivation was to get another desolation going so the heralds would return; Gavilar seems to have voiced this motivation at times too. However, it seems like his motivation went beyond that and he wanted worldhopping powers and to become a very powerful being.

Am I missing something or are some motives still unknown?