depends what you want. +1 valour gives a 1 attack and 1 defend and +2 morale bonus to your unit, while the metalsmith can give up to +3 attack.
so theoraticly the first gives you a nice balanced unit and the seconed gives you a buffed up shock unit.

I hope this whill help you in your choise.

But you could always use a code that gives all provinces iron (i only don't know what it was) but i does exists.