Member to equip with weapon (3)
I believe the answer is:
arm
I believe this is a double definition.
'member' is the first definition.
(member can mean a limb)
'equip with weapon' is the second definition.
(I've seen this before)
'to' acts as a link.
(Other definitions for arm that I've seen before include "Provide with weapons" , "strip of land?" , "5 [BRANCH]" , "Human limb" , "Ram into limb" .)