101Leafy researched the games.
Hidden Edge

Jet-black Sword. Rumors say the sword's strange vibe is hiding the lives it's taken.
| Class | Sword |
|---|---|
| Rarity | 7 |
| Attack | 266 |
| Affinity | 40% |
| Slots | 1 |
| Price | 80,000z |
Upgrades
| Upgraded from | Rex Talon |
|---|---|
| Upgrades into | Midnight Blades |
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 706.
Materials
Narga Scale+ ×6, Black Narga Pelt ×8, Narga Tail Spike ×4, Narga Brain Stem ×1