101Leafy researched the games.
Wailing Cleaver

Sword of regret and hope. A swordsman drunk on power, felled by a disciple.
| Class | Long Sword |
|---|---|
| Rarity | 9 |
| Attack | 960 |
| Thunder | 540 |
| Slots | 1 |
| Price | 100,000z |
Upgrades
| Upgraded from | True Devil Slicer |
|---|---|
| Upgrades into | Wailing Cleaver Shin |
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 692.