Personally, I feel that the combat, though involved in RP, doesnt have to be RP. Why? Because you're going to recount about the battle as a whole, not the weapons you used and exactly how you killed him. And, if none of you have ever fought in real life with weapons of any kind, you dont understand how easy it is to just switch weapons. Especially if you can duel wield. Using a basic minecraft strategy of opening with a sword then switching to unarmed and then to axes.
You can be pretty proficient in all of these. I know that in reality, its very easy to learn how to use many things well at once. If you duel wield a sword and a hatchet, or (though this one takes more getting used to) A sword and a onehanded battle axe, you can realistically be very good at both. And if the axe is too bulky and you want to attempt to switch to your bare hand, because say you have the persons sword or axe in a lock with your sword, you can. And you can very easily disarm them while they are distracted. Its all about being a good soldier. If you want to be the Solid Snake of medieval times, you can. Its just gonna take a lot of practice. And, as for bows, first of all composite bows exist. They are lighter weight while still offering a good amount of power. You may have one on your person, or maybe knew the battle was coming and stashed it on the battle field for later use. Say your opponent starts to run away, so you duck back behind something and get your bow, and start firing at him. You'll probably miss a few times, but if you're a good shot, you can hit them no problem.
Its possible to be proficient in all the combat skills, and a good soldier would use all the available options when needed. Its less likely that everyone is gonna know how to utilize their skills like this, true. But in a militant faction, an old experienced warlord could easily teach his techniques to the newer guys so that they understand. And then he builds a very reliable military of people who are proficient in all the fields of combat.
And as for the classes thing, it restricts gameplay too much. If you really enjoy that idea, go play a Heros server. personally, I dislike it. I dont like being so limited to doing one thing like that.