Gold Dust, its heavier than iron (which would make it better to club people around the head with), but more malleable, that means that it would be easier to use (harder to find, yes). The only thing you really have to worry about is melting it. And it would be good in a combination with lightning.
In my opinion, I much prefer gold because its a precious metal and one of the heavier ones. I read the periodic table too often. And gold is also resistant to rust, unlike iron which is highly prone to corrosion. Gold will last longer, but you would need to constantly take care of iron sand so that you can still use it. I know, oxydation sucks, but we can't stop it.