Weapon Triangle

Overview

The weapon triangle is a gameplay concept of the Fire Emblem series, describing the relationship between the three core melee weapon types:  swords, axes, and lances.  The concept was first introduced in the fourth Fire Emblem game, Fire Emblem: Seisen no Keifu, and has since been used as a key combat mechanic in all titles in the franchise.

The basic relationship between the weapons is:
Swords > Axes
Axes > Lances
Lances > Swords

When a unit wielding one weapon type faces off against a unit wielding its weak counterpart, the unit with the advantageous weapon receives a boost to attack and accuracy while the unit with the weaker weapon takes a drop in the same statistics.  Units that wield weapons outside of the three main types, such as bows or daggers, do not figure into this relationship.