(Ex) abilities help

I’m struggling to understand ex abilities.

I understand that they are supposed to be “non magical” representation. So for example a scouts heal is them actually bandaging you up instead of magic. So in turn it should get around Pro mag but not immunity to spirit or cursed.

I understand that currently under spongy you can cast any ability as a martial without having an empty hand,

But did ex before allow you to cast abilities without an empty hand?

Is there any other purpose for Ex abilities anymore or should it just be removed entirely?