{qama' qIppu'bogh neH yaS'e'}

This can mean "the officer who has merely hit the prisoner", but it can also mean "the officer who has hit only the prisoner". Right ?

No, because yaS'e' is also part of the relative clause. The entire relative clause, including its noun arguments, counts as a noun.

qama' neH qIppu'bogh yaS'e' the officer who hit only the prisoner

qama' qIppu'bogh neH yaS'e' the officer who merely hit the prisoner

qama' qIppu'bogh yaS'e' neH only the officer who hit the prisoner

-- 
SuStel
http://trimboli.name