Jeremiah 46:4 New English Translation

⁴Harness the horses to the chariots;
mount your horses!
Take your positions with helmets on;
ready^[a] your spears!
Put on the armor!^[b]

Jeremiah 46:4 tc The LXX reads προβάλετε (probalete), meaning “to hold before oneself, to present arms” (see LSJ s.v. προβάλλω B. III.). Instead of the MT’s מִרְקוּ (mir^equ), this may reflect an original הָרִקוּ (hariqu), from רִיק (riq), or הָרִמוּ (harimu), from רוּם (rum). Both readings assume a Hiphil form where the ה (he) was replaced by duplicating the מ (mem) ending the previous word. In Ps 35:3 the Hiphil of ריק (riq) means to draw a spear, while the Hiphil of רוּם (rum) would mean to raise [a spear]. tn Or “polish” or “clean.” The other three uses of the verb מָרַק (maraq) refer to scouring or polishing. The context refers to the final stages of battle preparations, so whether it was “polishing,” “drawing,” or “raising” spears (see tc note above), the main point seems to be to have them ready to use. Some translations say “sharpen” (NLT, NRSV), but this meaning does not fit the proposed readings and would be an earlier activity in battle preparations.
Jeremiah 46:4 sn A Hurrian loanword into Semitic. The Akkadian use refers to mail armor for either persons or horses.

New English Translation (NET)