I know this sounds like a really noobish question, but how do I get my gladiator to wield two weapons?

When I select a sword or dagger, it shows me the option of wielding it in my main hand, but I don't see the option of wielding it in my off hand.

I'm currently using a lvl 4 rage gladiator with a one-handed flail in my main hand if that makes any difference.

Thanks for any help!