101Leafy researched the games.
Hidden Breaker

Jet-black Hammer. A single hit feels like the weight of darkness descending.
| Class | Hammer |
|---|---|
| Rarity | 7 |
| Attack | 988 |
| Affinity | 40% |
| Slots | 1 |
| Price | 80,000z |
Upgrades
| Upgraded from | Striped Striker |
|---|---|
| Upgrades into | Deep Darkhammer |
Can also be made new at the smithy.
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 728.
Materials
Black Narga Pelt ×10, Narga Scale+ ×5, Narga Brain Stem ×1, Hrd Monster Bone ×6