[1.11.2] making a vary short range attack

[Friend2Creepers]

I've been working on a "assassin's knife" for a while, the main idea being if you get very close to a mob you can do around ~50 damage. Unfortuanatley I don't exactly know how to do this. I would love some help with finding a way to make this close range attack work. here is my code:

package com.idtech.item;

import com.idtech.BaseMod;

import net.minecraft.creativetab.CreativeTabs;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.projectile.EntitySnowball;
import net.minecraft.init.SoundEvents;
import net.minecraft.item.ItemStack;
import net.minecraft.item.ItemSword;
import net.minecraft.util.ActionResult;
import net.minecraft.util.EnumActionResult;
import net.minecraft.util.EnumHand;
import net.minecraft.util.SoundCategory;
import net.minecraft.world.World;

//advmod
public class ItemAssassinsKnife extends ItemSword
{
    public final static String name="knife";
    public ItemAssassinsKnife() {
        super(ItemMod.PhaKni);
        this.setUnlocalizedName(BaseMod.MODID+"_"+name);
        this.setCreativeTab(CreativeTabs.COMBAT);
        // TODO Auto-generated constructor stub
    }
    @Override
    public ActionResult<ItemStack> onItemRightClick(World worldIn, EntityPlayer playerIn, EnumHand handIn) {
        if (!worldIn.isRemote){
            
            EntitySnowball entitySwipe=new EntitySnowball(worldIn,playerIn);
            entitySwipe.setHeadingFromThrower( playerIn, playerIn.rotationPitch, playerIn.rotationYaw, 0.0F, 1.5F, 1.0F);
            
            worldIn.spawnEntity(entitySwipe);
         // TODO placeholder
        }
        return new ActionResult(EnumActionResult.SUCCESS, playerIn.getHeldItem(handIn));
      
    
    } 
}