101Leafy researched the games.
Bone Blade+

A Great Sword made with high quality bone. Not as sharp as steel, but very powerful.
| Class | Great Sword |
|---|---|
| Rarity | 1 |
| Attack | 384 |
| Slots | 0 |
| Price | 850z |
Upgrades
| Upgraded from | Bone Blade |
|---|---|
| Upgrades into | Bone Slasher, Red Stripe, Bone Katana "Wolf" |
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 680.