There are tons of spiky and pointy gardening tools in the garage. I could use some of these.
My primary plan was to come to them and swing my knife a little and just scare them.
If you just "scare them" then they won't know to fear you, just that you can swing a tiny metal rod around. You need to show them to NOT mess with YOUR brother.
You NEED to beat them up if you truly want them to leave you alone; if you prove your strength to them, you may even earn their respect.
Or their eternal hatred