Armsthrift (武器節約 Buki setsuyaku lit. Weapon Saver in the Japanese version, Parcimonie in the French version, Accortezza in the Italian version, Ahorro in the Spanish version) is a skill in Fire Emblem Awakening, which, when activated, will not reduce a weapon's durability.
Armsthrift is learned by Mercenaries at Level 1. When the user attacks or retaliates, this skill has a chance to activate. The activation percentage is that character's luck stat (including all skill, weapon, and pair-up bonuses) x2; thus, if a character has a total Luck of 50 or higher, it means that their weapons will never degrade.
Armsthrift is great for preserving Regalia weapons like Nidhogg, Forseti, and special forged weapons. Armsthrift does not apply to staves or using weapons for their curative properties, such as Hauteclere.