If he cannot revive her, there are a few things I suspect.
One is because of the protection of whatever Gods they worship, her soul, apart from her remains, cannot be affected by Necromancy because of their protection or blessing.
The second which I think is more likely is, that her soul has...
The entire family seems to be hostages. Each one is being used as leverage to force another to cooperate. Yumi though, is potentially a ticking bomb. If she regains her Hero Drive and discovers Makube is holding her father, and maybe even her mother, prisoner, just what would a kid that age...
I'm gonna guess he decided to give the plot development more thought than quality control of the art, since it would become the foundations of wherever he could take the story from now on. I mean, that was quite a lot of political and economic influence being flexed in this chapter.
Credits...
Agreed. Since he already gave them the method, he's of no further use. Let him walk past smugly, then take his head. Heck, put a 9 through his cranium, if you could.
Like rings in our world, it may depend on the design, what it's made of, and where and how it's worn. From the other two, it looks like that specific meaning comes with a gold bracelet, not a woven one.
On a separate note, after handing over the diagram, now Hiro wonders if he can trust him...