There are very few dragon items in Runescape Classic. The few that were created before Runescape 2 was released are:
The Dragon Axe provides a +70 WeaponAim and a +85 WeaponPower bonus. This is the highest weapon power bonus for any weapon. It requires 60 Attack to weild. You can get the Dragon Axe by purchasing it in the Hero's Guild for 200,000 coins after completion of the quest.
The Dragon Medium Helmet provides a +34 Armour bonus, giving it the highest defense for any helmet. The helmet requires 60 Defense. You can get Dragon Medium Helmets by killing King Black Dragons and some other high-leveled monsters.
The Dragon Square Shield provides a +50 Armour bonus, giving it the highest defense of any shield. The Square Shield requires completion of Legends Quest. You can get the square shield by buying one half for 750,000 coins, then getting the other half from drops of Shadow Warriors. You need level 60 smithing to combine the two halves of the shield, but you do not need it to wear it.
The Dragon Sword provides a +71 WeaponAim and a +71 WeaponPower bonus. This is the highest weapon aim bonus for any weapon. It requires 60 Attack to weild. You can get the Dragon Sword by purchasing it for 100,000 coins in the Zanaris marketplace, paying 1 diamond for entry and after completion of the Lost City quest.