Armor:

Emissive

Emissive causes the entity to glow when they have a helmet enchanted with it equipped.

Suggested by RDKRACZ

Fire Strike (internally named FireThorns)

Fire Strike acts like thorns but sets the target on fire for level seconds. Can be applied to any armor.

Last Stand

If the users health is lower than 1 heart when they are attacked, they will be randomly teleported away using enderman teleport logic (internal interface ITeleportRandom). Can be applied to chestplates.

Marathon

Marathon is an enchantment that decreases hunger used while sprinting. It causes hunger used to be halved. Can be applied to boots.

Swift

Makes the player move faster when they have this enchantment. Under the hood, it gives the player the Swiftness effect constantly, invisibly, with potency equal to level - 1. Can be applied to boots

Weapons:

Aerial

Acts like knockback but launches the target upwards instead

Adrenalin

If the use has less than 30% of their full health when they attack something, a futher 1.5x of damage will be applied. Can be applied to any weapons. This still needs massive balance changes, it is currently very op

Aqua Aspect

Aqua Aspect is like sharpness, smite etc. but for fire and end mobs (CustomEntityGroup.HURT_BY_WATER). The added damage is equal to Level * 2.5, the same as the sharpness enchantment.

Butcher

Butcher is like sharpness, smite etc. but for animals. The added damage is equal to Level * 2.5, the same as the sharpness enchantment.

Disarm

5% chance the target will drop the stack in their hand when you attack them.

Suggested by RDKRACZ

Frost

Frost gives the target slowness (with potency equal to (level - 1) / 2 and duration equal to 20 * 2 * level) it also causes the mob to trail snow for 20 * 2 * level seconds using the custom ISnowy interface.

Haphazard

Haphazard is a fairly complex enchantment. Whenever the weapon it is applied to is used to attack something, it chooses an event from a list randomly. The documentation for these events are on a separate page labelled Haphazard Events

Strike

4%/8%/12% chance that the target will be struck will lightning on attack.

Suggested by RDKRACZ

Vampire

When the target is killed, the user gains 0.5 * level health (player health is measured out of 20). This will likely be changed to give a percentage of the target's health to make it more balanced

Warp

When the target is attacked, it has a 25% chance to be teleported away using the ITeleportRandom interface. The teleport logic is the same as the Enderman random teleportation.

Curses:

Curse of Bluntness

Decreases a weapons attack damage by 5

Curse of Hunger

Gives the user 3 seconds of hunger when they are damaged

Curse of Slipperiness

When the weapon is used, there is an 8% chance the item will be ejected from the inventory

Curse of Snow

Causes the user to trail snow like a snow golem