How can you wield dragon in RuneScape?

Answer 1

In order to wield dragon weapons, you need to have high enough levels (usually level 60) and in most cases a quest.

To wield different weapons, you need to do different quests.

For instance:

to wield dragon long-swords or daggers, you need to do the lost city quest.

but in order to wield the dragon scimitar, you need to do the monkey madness quest.

The runewiki has a list of the quests required to wield the different dragon weapons.