how to increase sword sweep?

You could try using an entity iterator to target and damage all entities in a larger radius than is normally allowed. By default, an entity iterator targets all entities in a box centered on a provided position, and then runs code on each entity individually. You can use if brackets inside to check if the entities are of a desired type... or if they're in the desired direction. (If you want it to only be entities in the player's field of vision, instead of all entities in a radius, you could use some math to determine whether or not the position of each entity relative to the player is in the direction they're facing.)

You essentially need a procedure that triggers when the player swings your item, that runs an entity iterator, which damages each entity in your desired radius, if they meet your conditions.

Just make sure everything inside the entity iterator is targeting the entity iterator, (the currently selected entity), not the event/target entity, (the player who's using the sword.) You also probably want to check that the entity iterator does not equal the event/target entity. (Otherwise the attack will also damage the player, since they're in the radius.) I could send a screenshot of an example procedure, if you need one.