Apart from cases of salmonella outbreak, that fruit can be lethal is a remote thought—except perhaps when army experts hightail it to a sleepy Lebanese mountain town for a controlled detonation of a hand grenade, or as the local usage would have it, a “hand pomegranate” (رمانة يدوية). 

Produce-inspired sobriquets for hand grenades are not exclusive to Arabic.

To American GIs the oblong, knobby Mk II hand grenade of the early twentieth century suggested not the smooth Mediterranean pomegranate, but the pineapple, which was hardly more local, but almost certainly more familiar.

For its part the German Wehrmacht had first its “egg hand grenade” (eierhandgranate) and later the longer range “stick hand grenade” (stielhandgranate). Given Teutonic dietary sensibilities and the weapons’s resemblance to the ubiquitous kitchen implement it quickly acquired the moniker “potato masher.”

What sets the Arabic “hand pomegranate” apart is that it refers not to a single production of hand grenade, but the entire class of weapon for which Modern Standard Arabic generally, but not always, uses the more strictly literal “hand bomb” (قنبلة يدوية). Dialectical use routinely differs from formal registers, but it is somewhat unusual for usage to vary seemingly without reference to patterns of influence by foreign language (often French or English) or relations based on military cooperation, arms supplies, advisers, and the like (ditto).

“Hand pomegranate” comes up in Tunisia as well as Lebanon, where it sees both popular use and mention in Lebanese Armed Forces communications. Meanwhile in Syria, which was also in the French sphere of influence, “hand bomb” is apparently more common.[1] Conversely, “hand pomegranate” is also used in Iraq, where Britain was more influential.  

[1] Defense Language Institute, Foreign Language Center, Arabic: Syrian Dialect (1985), Module 8, Lesson 29, 16.