I can't really speak on ESD killing diodes, I've never killed a diode from ESD. I live in the tropics, so the humidity is always too high for static electricity. However, you could just manually attach some wire to your iron and ground it.
Although, unless you have an ESD safe workstation, grounding your iron isn't really gonna help, in fact it could make it worse, since the static is usually on your body, not the iron.
Although, unless you have an ESD safe workstation, grounding your iron isn't really gonna help, in fact it could make it worse, since the static is usually on your body, not the iron.