Demon Bow

The timing is what makes this worth building. Beating the Eye of Cthulhu once drops enough evil ore in a single go to cover the bars, so the bow is usually available the same night you win, with no extra mining trip attached. That drops a real ranged upgrade into your hands right as the caves start throwing tougher things at you.

It does apply knockback, so the full reforge pool is open and Unreal is the target once you can afford the gold. Corruption worlds get this one, Crimson worlds get the equivalent built from their own ore, and the two are close enough that neither is a reason to reroll a world.