In case you are reading anon, Warsmiths are just the fluff-alias for Iron Warriors Chaos Lords.
Back in 3rd edition, the Iron Warriors had a special rules that allowed them to buy Servo Arms for each model, which game them an additional powerfist attack, which is what this model is representing.
To stay fluffy, for Iron Warriors, you want to stick to Warpsmiths (which you can kitbash out of this Warsmith model if you want to; just add a few mecha-tentacles) and Chaos Lords to hand out rerolls (which you can just use this model for if you want to). To expand on fluff, you can grab a Renegades and Heretics Detachement and play a Basilisk, just like in the old days.
For Emperors Children, Lords and Sorcerers are fair game. I would keep some reserve points to summon Daemonettes, Seekers and/or a Keeper of Secrets in the midst of battle.