Hammerne

Hammerne is a staff that restores one of an adjacent ally's weapons to perfect condition. In many cases, there is only one Hammerne staff in each game (two in Fire Emblem: The Sacred Stones). It cannot be repaired using another Hammerne staff. In most cases, the Hammerne has very few uses before it breaks, so it should only be used when necessary, and on rare weapons. In Fire Emblem: Rekka no Ken, it seems, instead of repairing items like in the other games, to "steal" the item and replace it with a new copy produced out of thin air, as when the player attempts to restore Legault's Lockpick, a help dialogue will appear stating that this item "cannot be stolen".

Obtaining/Usage
In Fire Emblem: Ankoku Ryū to Hikari no Tsurugi, it has twelve uses. It can only be used by Lena.

In Fire Emblem: Monshō no Nazo, it has five uses and can only be used by Rena, and her pupil, Malliesia. When cast, its user gets 58 experience points.

In Fire Emblem: Thracia 776, it has five uses and can only be used by Safy. What about Sesin no Kiefu? (Fire Emblem 4?)

In Fire Emblem: Fūin no Tsurugi, Fire Emblem: Rekka no Ken, and Fire Emblem: The Sacred Stones, it has three uses and can be used by any staff wielder as long as they have an A rank in staves.

In Fire Emblem: Path of Radiance it can be obtained in a base conversation in Chapter 23: The Great Bridge. It has three uses.

In Fire Emblem: Radiant Dawn it can be obtained by visiting the northernmost tent on Chapter 3-3: River Crossing.

In Fire Emblem: Shadow Dragon, it has twelve uses, can only be used by Lena, and gives fifty points of experience to its caster.