The additional information revealed at {qep'a'} 24 (2017) is that {'uch} can be used in a weapons context to mean "locking on a target": {DoS 'uchta'} "he/she locked on the target".

It was also revealed at the next {qep'a'} (2018) that {'uch} can take {'olQan} as its object, in which case the expression is often translated as "occupy" or "take up" (space).

These are obviously meant to be applications of the same verb, but if the weapons-related meaning were to have a separate entry (which it does in {boQwI'}), it should be something like "lock on (a target)". The definition "grasp" is already in KGT.