The Safe Helm gives the wearer a permanent Protect effect, which is very powerful against Physical attacks. If you're going into battle against an opponent who eschews magic, this is a fantastic piece of gear.
Finding Safe Helms isn't that easy, however. You can get one in the Forest Ruins, but you'll have to forego Crono's SwallowWeapon. In the long run the Safe Helm is more useful, so it's not a bad choice. You can also steal them from Lavos SpawnShells in the Black Omen, but expect a powerful counterattack when you do.