Helmet is a must. You head is the tallest part of your body, therefore when you smack the ground after a edge catch, the head will have the highest velocity hitting the ice/snow/pavement.
For typical riding, knee and butt pads are great to have. The safest way to reduce a toe edge fall is to try to drop on your knees first when possible. This is where kneepads helps a lot. You knees are one of the lowest part of your body that can aid to reduce impact. You really don't have much choice on your heel edge falls except to take it in the butt.
So wear that butt pad.