I think a lot of the examples you used could better be described as Zanshin (presence). From wolves to thieves, they thrive on fear. In the cases you mentioned the aggressors (actual or potential) sensed this was not victim.
Prefer to read Ki as spirit in this context but not enough to quibble - mind works ok also.
However I see Kiai as much more explosive than Zanshin and as I am sure either of the Chuck's will be quick to point out (they've done so before) sound does not have to be involved.
Your story about your sensei's grandfather comes closest to kiai but even there the shout probably just brought attention to a man with a reputation. Zanshin once again.
As per Ki balls - please someone name a respected Budo (not Japanese manga) that actually refers to this concept. My Japanese sensei doesn't cut it - there are a lot of fools and charletons here also. I would want to know what he practices.