Can I use a star as a weapon. Drop it out horizontally. If you hit the player, he dies. Sorry for English (Google Translate)
Yes, create a class extending Projectile and refer to the ItemEntity class's sendSpawnPacket and copy it over to your new projectile class. You'll need to modify that function to make it show up as a nether star item entity. Set the gravity of the nether star projectile to 0.0.