Sounds good so far. Nice and dark like most of the LE nations. I find late age a bit depressing, prolly why I don't play it much.
The thought of an underwater blood nation is intriguing if only because it's not been done. They would most likely need several unique blood spells and summons since most (if any) aren't castable underwater. But that would make them the first underwater nation with national spells.
Whatever you decide, it will be good. I'm consistently impressed with the mods in this community.