Fencers blades + Ironfist

Are you able to have Fencer's blades and an Ironfist on the same model?

In short yes. However you will only gain the benefit of the Ironfist against Ranged / Shooting Attacks. As the Fencers Blades are a Pair of Weapons they require 2 hands to use in combat and cannot be used with the Ironfist. This goes for Mundane or Magic paired items as far as I recall because if you have a "special" weapon then you must use that over your hand weapon. There are a few exceptions to this rule (Black Orks for example) however Ogres have no way around this rule.