Sword That when i hit a mob it gives the player food point

trigger: on attack

if (source entity) is sub type of player

  if item in main hand of (source entity) is (item)

    set food saturation of (source entity) to (get food saturation level of (event/target entity) + 5)

maybe swap where the sword and the item in main-hand is.

Your Issue is, that you use "the set food saturation" block (saturation is like an invisible parameter that decides how long it takes to lower the first piece of the hunger bar) What you want to use is the "set food level of" block that actually adds hunger to your bar. Otherwise it should work with all the entity blocks being "source entity".

Another maybe code efficient way of achieving your goal is to go to your custom Item, then triggers and add the procedure to "when living entity is hit with item". The procedure can look like this:

and you can add the procedure here:

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