What is the best weapon on runescape if you have 80 attack strength and defence

The best weapon is debatable. I personally have 81 attack, 88 strength and 82 defence. As far as weapons go I would say if you have 75 magic get a staff of light as its combat stats are better than whip and it is one speed faster than that of the dragon scimitar and it is only one handed so you can weild it with a dragon defender. it also has a special attack that reduces all melee damage you take by 50% for one minute, and it raises your magic attack spells damage by 15%. If you do not have 75 magic however make it a point to use a dragon scimitar if you are short on money, if you want a better option and have money use a berserker necklace and an obsidian mace (Tz-Ket-Em). If you have a great ammount of money and are only interested in training strength then a saradomin sword is a great option. If you want to train attack go with an Abbysal whip, it's accurate and fast. As far as defence goes, you can also use a whip for it, or if you ccan afford guthan's (Barrows set) as well as repairs for said set, you can train defense at aggressive monsters as Guthan's will heal you (however, be warned, Guthan's is not a sure-fire way to fight without food (always bring a few pieces of food to heal you))