Think of it this way, the amount of force that a push uses is set, weight only changes which object is moved.
I don't recall Wax tapping for more push on coins/bullets, but it's been almost a year since I read WaW.
remember, we're seeing that from their view, they are not reliable.
Nale is trusted to lead the Skybreakers, Kalak was trusted as a Judge, Ishar is trusted as a king, etc etc.
I think that she was starting to go insane, and Raboniel was trying to stop it to be far more likely
The Stormfather is a shadow as well, and he's been around since before the Shattering. But he is a spren too, so he's weird
It's a common theory that they were once spren of H/C but it wasn't until the False Desolation that anyone realized that Unmade could be trapped in gems.