You can duplicate infinite Rewarp staves consistently using this method.
First, you need a character who's about to Level Up.
At the start of the turn, they must have the Rewarp staff in their first slot (unequip your weapon, select the Rewarp staff and choose Arrange) and at least one weapon in their inventory (that you don't want--it will be PERMANENTLY LOST).
Use the Rewarp staff to Level Up. You'll notice your character has automatically equipped one of their weapons.
Now use the Time Crystal to go back one step. You'll now have an extra Rewarp staff, at the cost of the previous equipped weapon.
If you have multiple weapons, you can repeat this step for as many weapons as you're willing to sacrifice.
You can also sacrifice Engage weapons! They come back afterwards, but you may want to triple check first...
I tested this with multiple staves and only Rewarp seems to work. Unfortunately, Entrap, Warp and Fortify don't work.
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