What does it do :

Adds sharpness support for tridents

Adds looting support for tridents

Melee damage : 9->10

Ranged damage is based on range, max 10

Attack speed (in game logic) : 1.1->1.3

Attack speed (in seconds, time between hits) : 0.9->0.75

With sharpness V :

Melee damage : +3=13

Ranged damage is based on range, max 11

NOTE : Tooltip damage, the one shown in your inventory, is broken. It won't fetch the real damage but rather the one of that item in the game code, from what I understood. So it will show 9, but deal the above values.