Seraphim are spirits of the land! I mean, that's the most common word for Mikleo's people anyway. As for what resonance is...

Actually, I have no idea how to explain that further. It's a sense? Or a skill, since it can be honed... Um, maybe it's more like a feeling, that as it gets stronger helps you to see more of the world around you. I heard that being devout and grateful can help with that, but that's probably just because seraphim are more likely to hang around if people appreciate them.