A bow and arrow does not have to be a Valentine's day reference, although everyday can be Valentine's Day if you want it too! Cupid is the most famous Valentine's Day symbol, and he's always armed with a bow and arrow. The arrows signify desires and emotions of love, and Cupid aims those arrows at people, causing them to fall deeply in love.
However, bows and arrows are also used as a weapon, either for hunting or other activities.
Interesting how in one way, a bow and arrow causes people to fall in love, and in the other way, it can do the complete opposite, and hurt people.
Sources: History of Cupid ~ The God Of Love !