Since when is anything balanced with realism in mind when it comes to plate armor?
I'm pretty sure that hitting a plate armored guy with a light slashing weapon or a light blunt weapon on the chest shouldn't do jack shit, but that's obviously not how it works ingame.
Throwing just suffers a particularly large amount in overall killing power whenever they hit arm/hands from enemies raising their weapons since they have a small ammo pool, and they suffer more from weird crpg weapon slot/warband weapon slot logic.
With archery/xbow picking up ammo is less of an issue because you generally have enough ammo for a round unless you shoot from far away for a very long time, and you can avoid pickup bugs/having dead weight by dropping your quivers just by dropping your ranged weapon. With throwing you'll generally spend a lot of ammo very quickly upon engaging, and you can't drop "spent" throwing weapons, so you'll get screwed by buggy scavenging and artificially high weapon weight.
Some sort of workaround for cases like a single throwing lance taking up two slots, and two throwing lances of differing heirloom levels taking up 4 slots would also probably be handy.