Eh...the spear IS a weapon. You cant really use it as anything else :P Maybe to grill something over a fire!
supernumeraries are also known as spear-holders. Spears can be used as props (i.e. properties)
Does δόρυ have something in common with Dorians?
Όπλο was gun in another exercise I am assuming it can mean either
Yes, όπλο means "weapon" as well as "gun".