Yeah, shield seems useless for duels (at least for me with my huscarl shield), it makes blocks so much slower. Maybe it feels different for fastest shields though.
Also I don't get why some people think using knockdown in duels is unfair or honorless. You see, if swordsmen can abuse their speed and reach, axe wielders abuse their damage and shieldbreaking, why can't blunt weapon users use the natural advantage of their weapon? If they don't, they become highly underpowered.
And when I offer duel to some good fighters like Hearst, duel points make me feel like "Can I try to get shitloads of points for killing you?" instead of "Can I learn something by duelling with you?". Makes me feel awkward.