To earn this achievement, you need to purchase the upgrade for weapons and armor from 5 of the legendary blacksmiths for ONE character. These blacksmiths are located on:
Theramaga in the Roddenberry system
Pectoralis Major in the Turing system
The Lost Moon of Vorkar in the Clarke system
Uranus in the Sol system
Neo Tokeeo in the Leguin system
The game does not keep track of which upgrades you received, so you have to.