" Armour in Warband is low-poly, so it relies on normals for smoothness. Try recalculating normals in OpenBRF (experiment with the smoothness slider). If that doesn’t work, you’ll need to export the armour to a 3D program such as Blender where you can smooth it in object mode, add a smoothing modifier or add a sub-surf modifier to increase underlying geometry. "
ohh , thx . i'ii try that out.