So... vIp is described as meaning afraid... In this phrase, it looks to me the meaning is don't worry if you kill a coward. So is this an acceptable interpretation?
could worry, or get anxious, or fret also be translated with the -vIp suffix?
No. The suffix -vIp talks about actual fear of the action occurring, not simply concern about the difficulty or consequences. Those could be things that play into the reason for the fear, but they are not necessarily implied by the fear.