public class ItemPoisonSword extends ItemSword {
    public ItemDumbSword(ToolMaterial materialIn) {
        super(materialIn);
        setRegistryName("item_poison_sword");
        this.setUnlocalizedName("poison_sword");
        setCreativeTab(CreativeTabs.COMBAT);
    }

    public boolean hitEntity(ItemStack stack, EntityLivingBase target, EntityLivingBase attacker)
    {
        stack.damageItem(1, attacker); //The first number is how much damage you do, probably more than 1.
        attacker.sendMessage(new TextComponentString("hitEntity Method Called"));
        target.addPotionEffect(new PotionEffect(Potion.getPotionById(10), 100, 3)); //The 10 is the ID of poison, the 100 is duration and 3 is how much it's amplified by.
        return true;
    }

}