How does this sound?

Instead of manually trading with every settler, you would store weapons, ammo, and armor in a special Armory container, so your settlers can freely use them when under attack.

Already suggested here: http://www.gamesas.com/topic/1560484-settlement-guns-armor-rack/

You can equip settlers by yourself already. Just trade, give them stuff you want and hit the equip button (T for default).

Aside from the fact that OP mentions 7 words in that it would be alternative to that.... trading and equiping 16+ settlers in a number of settlements is kind of redundant. They can hop in your power armor, why couldn't they run and grab a rifle