Let the generator decide a random weapon to collect before each boss fight.
There are a plethora of unique and obscure weapons in Terraria. Even if the weapon isn't ideal for fighting the boss, hopefully you can experience using a weapon you would have otherwise never used!
Note - Progression assumes the following boss order:
Pre-Hardmode: King Slime, Eye of Cthulhu, Eater of Worlds / Brain of Cthulhu, Queen Bee, Deerclops, Skeletron, Wall of Flesh
Hardmode: Queen Slime, The Twins, The Destroyer, Skeletron Prime, Plantera, Golem, Duke Fishron, Empress of Light, Lunatic Cultist, Moon Lord