101Leafy researched the games.
Tarnished Hammer

A tarnished Hammer that isn't good for much as-is. But if you polish it...
| Class | Hammer |
|---|---|
| Rarity | 1 |
| Attack | 572 |
| Slots | 0 |
| Price | 2,500z |
Upgrades
| Upgraded from | Rusted Hammer |
|---|---|
| Upgrades into | Breath Core Hammer, Jadite Mace |
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 726.