101Leafy researched the games.
Atlas Hammer

Crafted from superior bone, this Hammer boasts improved Attack. The standard-bearer.
| Class | Hammer |
|---|---|
| Rarity | 2 |
| Attack | 572 |
| Slots | 0 |
| Price | 1,750z |
Upgrades
| Upgraded from | Cyclo-Hammer |
|---|---|
| Upgrades into | Kut-Ku Jaw, Jail Hammer, Khezu Horn |
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 722.