20 AC is not overly high for 3rd level, to be honest.
If you are married to shield and 1h weapon I'd go with a craghammer or a waraxe, remember to take the associated feat at Paragon tier.
I *personally* am not a huge fan of cleave, since it is kinda situational, but as your other at will is fine I won't nitpcik. I like the fighter in our games take, he has tide of iron and footwork lure, allowing him to push or pull whomever he hits.
Have you looked at dwarf stoneblood? Good feat?
Also, I don't get when you say that you don't use chain because you already were playing this character when martial power came out, yet he is using a fighter build from that book? If you will retrain his fighter build, don't be afraid of changing his preferred weapon. That challenge attack you get on marked baddies should *hurt*, and you can't pass up opportunities to pile on the hurt.
Jay