Where does “flāgmen” come from?

flāgmen (Proto-Italic) comes from Proto-Indo-European bʰlag- — to hit, strike, beat; to strike.

Ancestry of “flāgmen”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	bʰlag-	to hit, strike, beat; to strike

flāgmen — Etymology, Origin & Word History | Etymology Explorer