101Leafy researched the games.
Feather Sword

Curved blade that causes Sleep, like its namesake. It leaves a lasting impression.
| Class | Sword |
|---|---|
| Rarity | 9 |
| Attack | 280 |
| Sleep | 200 |
| Defense | +7 |
| Slots | 2 |
| Price | 80,000z |
Upgrades
| Upgraded from | Feather Knife |
|---|---|
| Upgrades into | Hi Feather Sword |
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 702.
Materials
OrangeHypnoPelt+ ×5, Eltalite Ore ×10, Hypno Bezoar+ ×1, Lg Pelagus Fang ×2