/wizards kit edit <kit> or /wizards kit export <kit>.
The edit command will open a inventory so you can see the kit items and change each piece, you will receive a message to confirm the changes after closing the inventory.
The export command will drag everything from your inventory to the kit.
A backup of the kit file will be created before appying the changes.
Added potion-effects to kit and classes
POTION_EFECT : DURATION : LEVEL
Just add "potion-effect" as a list to the class file/kit.