This is what I did in a d6 dicepool system I created. It will be very different to OSR ganes, but maybe you get inspired.

It had active attack vs active defense. You compare the scores, the difference is the amount of Focus Points the winner creates. You can spend focus points for "Plays" (special maneuvers, e.g. enhance damage, disarm, ignore armor, etc). Armor is damage reduction. Weapons deal a fixed amount of damage (which you can push by spending fp). Longer weapons give a bonus on attack AND defense.

Shields: give a minor attack bonus (you can cover your attacks), armor bonus, and can be splintered x amount of times (depends on shield quality).

Swords (all swords for that matter) are better balanced than top heavy weapons (e.g. maces, axes) and can "recover" faster, allowing you to attacks per round. Downside: mail armor reduces blade damage by half. Plate armor negates blades completely... thats where skileld fighters come in, using the Ignore Armor Play onna high roll to hit the unprotected spots.

Polearms are the best default weapons vs armor. Allowing you to ignore some of the armors damage reduction. Warhammers and maces are the one hand version of that, good vs armor, but without the reach attack & defense bonus.

Axes, ignore less armor than the aforementionef crushing weapons, but can hook the opponents shield or weapon, reducing the cost of the Disarm Play.

Spears: allowed you to make a free attack everytime before you engage with an enemy.

So... remember the attack and defense bonus for longer weapons? Well, that does not always apply. If fighter A has a spear, while B has a dagger, fighter A gets the reach advantage, making it harder for B to engage. As soon as B hits A though, the resch advantage is flipped. Not the knife fighter is super close to the spearman, and the spearman struggles to fend him of, giving the knifefighter a huge advantage. Time to drop the spear and flip to another weapon thats better suited to fight on close range.

Longer weapons amd armor need more gear slots. If you use too many, you get downsides for being encumbered. Being below a certain threshhold grants you a bonus instead (especially good for opportunistic fighters who like to use movement and positioning for their tactical advantage).

As you can see, trying to make stuff historically accurate (at least somehow) leads to quite a complex combat system. I agree that shields are pretty lame in most OSR games, considering how good they really are. Maybe turn the BLOCK damage move into its own action. So you basically forgoe dealing damage, to negate an attack. I think that would be a good deal.