Well, it's debatable as to what is the best weapon seeing as everyone has different preferences in them, but normally, it would be said that any Godsword qualifies for the best sword in the game. Within this as well, there are preferences, seeing as some people has 'allegiance's' to certain RuneScape Gods.
Dragon claws
Saradomin sword or Dragon scimitar are popular.
I'd say either a Dragon Scimitar, or Abyssal Whip.
sorry but to wield a dragon weapon you need to have the required level of 60 attack.
Dragon Dagger, Dragon Battle Axe, Dragon Longsword, Dragon Halberd ----------------- Mainly out of those, Dragon Dagger P++ and Dragon Battle Axe are best. EDIT. dragon claws are better.
the most expensive: blue partyhat the most useful combat weapon: corrupt dragon scimitar
The bronze dragon claw does nothing much it isn't a a weapon or such in runescape it is just a artefact that is sold to nastroth in lummy for 20k nothing else
Dragon arrows
By training on monsters like dagannoths, bandits, or fire giants with a good weapon like an abyssal whip, or a dragon weapon like a dragon scimitar.
The best monster to kill in Runescape would be the King Black Dragon.
The corrupt Dragon 2h is best tradable weapon on F2p, although is degrades rather fast. The Gravite 2h is not purchasable with gold, rather Dungeoneering tokens, and also degrades, but is the best weapon in Free-to-play.
Gravite shortbow.