We have a warrior. He owns and wears a gambeson, a mail hauberk, an open steel helmet, all necessary clothing and a good pair of boots. He is looking to reinforce his armour with a few select parts of steel plate, but doesn't want to wear anything too massive like a full cuirass (he tried and doesn't like how it feels). He doesn't like brigandine either.
His weapon of choice is a polearm probably best described as a partizan. He uses a longsword for backup and obviously carries a dagger as well. He can't use shields because of an injury to his left arm. He also mostly fights in smaller skirmishes rather than large field battles, for which he would be willing to equip heavier armour but doesn't plan to buy this at the moment.
The technology level is fictional late medieval. Full plate exists, firearms do not, magic is not part of this equation and the necessary budget is available unless seomething is extravagantly expensive.
Currently our shopper is eyeing gauntlets, greaves, possibly spaulders and a gorget. But what do the experts recommend?