101Leafy researched the games.
Fatalis Blade

Those holding this blade are forever locked in struggle with the elder dragons.
| Class | Great Sword |
|---|---|
| Rarity | 8 |
| Attack | 1008 |
| Dragon | 250 |
| Slots | 0 |
| Price | 100,000z |
Upgrades
| Upgraded from | Black Blade |
|---|---|
| Upgrades into | Black Fatalis Blade |
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 688.