101Leafy researched the games.
Rusted Sword

A rusty Sword that isn't good for much as-is. But if you polish it...
| Class | Sword |
|---|---|
| Rarity | 1 |
| Attack | 126 |
| Slots | 0 |
| Price | 1,250z |
Upgrades
| Upgrades into | Tarnished Sword |
|---|
Upgrade tree from モンスターハンターポータブル 2nd G 公式ガイドブック (Enterbrain, 2008), page 706.