Moved all skill references to an enum which is used throughout the codebase for reusability
replaced Tier with Minecraft's built-in Rarity and updated all references to use this instead.
This also allows for adding UNCOMMON at a later dater. Alternatively you could downshift rare and epic to uncommon and rare respectively and then add the higher epic. I just didn't want to refactor all of your filenames if that wasn't an intended outcome.
in the finishUsingItem method replaced the registry lookup to ALL_BOTTLES with a reference to the item itself.
Removed some helper methods that were only used once and were otherwise reduced to one line. namely applySkillEffect.
Rarityand updated all references to use this instead.finishUsingItemmethod replaced the registry lookup to ALL_BOTTLES with a reference to the item itself.applySkillEffect.