[PvK]

Black Lord with Fire Brand and Charcoal Shield forged by a Master Smith with a Dwarven Hammer. Put 2-5 Black Knights in a squad with him on Guard Commander, and him on 0-5 Hold orders followed by Attack Rear or Attack Archers or something, and place them on the flank of an army. Maybe also some other Black Knights in a squad on Hold & Attack Rear, and/or other thug squads.

If he's a good one or you want to invest more gems, Marble Armor and Bracers of Steel. Without research you can also forge a Sword of Sharpness which is a good worthwhile boost to both offence and defence. If your enemy is using MR-resisted spells, add an Amulet of Antimagic.