IPA: /ˈɑːrmər/
KK: /ˈɑːrmər/
A person who makes or repairs protective clothing and equipment, especially for soldiers.
The armourer carefully crafted a new suit of armor for the knight.
Armourer is formed from "armour" (from Old French *armure*, meaning protective covering or equipment) and "-er" (meaning a person who). An armourer is a person who makes or sells protective equipment, particularly for soldiers.
Think of someone who provides 'protection' ('armour') and is a 'person' ('-er') — that's what an armourer does.