Buster Greatbow

Weapon (long bow), very rare (requires attunement by a creature with 18 or greater strength)

This mithril longbow uses your strength score instead of your dexterity score for attack and damage rolls.

Attacks made with the Buster Greatbow are magical and do 1d12 piercing damage. You gain +2 to attack and damage rolls made with this weapon.

Crowd Buster. Once per day on your turn you can make an arrow shot from this bow send out a shockwave. In addition to the normal effect of the attack, the shockwave deals an extra 2d8 force damage in a 10 foot burst. Creatures within the burst must make a DC 12 Dexterity saving throw or be knocked prone. A nonmagical object not being worn or carried also takes the damage if it's in the burst.

Chaos Zweihander

Weapon (greatsword), legendary (requires attunement by a chaotic creature with 18 or greater strength)

This greatsword has a reach of 10 ft. and does 3d6 slashing damage. When a creature first attunes to this sword its attacks are magical, but it does not have any bonus to attack or damage rolls. When you use this sword to strike the killing blow on a humanoid creature the sword grows stronger. As more humanoid creatures are slain by this weapon it gains a bonus to attack and damage rolls. It also gains additional fire damage.