Idea:
Remove the ~10 second charge-up after every Rocket Boot use.
More information:
Even though the Rocket Boots are 5 Emeralds, they are nearly obsolete and have no reason to buy them. The boost itself is directional and cant even jump between platforms, using the item deals 5 damage (2.5 hearts), the cooldown period is too long (around ten seconds), and they only have ten uses.
The thought to remove the cooldown means you CAN boost between islands more effectively, at the cost of more damage to the user, and damage to the Rocket Boots item overall.
Even making the damage taken from multiple uses increase per-use is understandable, after all, they are sticks of dynamite taped to boots.
Also, the Feather Falling is a nice touch. No notes.