Dagger Ninja in Metin2 can do insane damage on higher levels in Metin2, based on this and their skills (Metin2 yang) offer ability to make your target poison. It will be a bit difficult for you to play at the start, but as the skills and levels rising, the power will also increasing.
1. Rolling Dager: lasting poison + 3 hits combo make it really powerful and useful skill.
2. Ambush: skill which is needed for bots ways: PvM and PvP. Extra damage from stealth and backstab attack makes it main skill, which will deal the most damage.
3. Stealth: pretty useless in pvm. You can use it from 1k fighters after 75, but it is still not the best advantage.
4. Fast Attack/Poison Cloud: you can go for fast attack since you will be fighting from foot after level 50, the damage from fast every 15 sec is much better than low damage + like 20% poison from cloud. But if you are planning to exp from horse, cloud is a better idea. Choice is still yours.