I just hope they separate blade into short and long blade. Why the hell would I as a thief be able to swing a claymore as good as a skilled warrior? And like so many people have complained about before,
this is getting quite old but for the love of God bring back spears! Other than that, i'm completely fine with melding speechcraft/mercantile and athletics/acrobatics.
A general basic melee weapon might be enought for low level. It is the basic of dodging, parrying, moving around, anolysing your ennemy tactic, coordinating your body moves to hit where you want to. Now, each weapon is specific and should be trained for to be used at its max potential, and that is where we can see the perks putting the specialisation between a dagger and a claymore user, making the character more skilled with one than the other.
But if the game was designed properly, there would be an obvious reason for your thief to take a dagger : encumbrance. Climbing with heavy weaponry should be hard. Collisions of weapons with the environment should also be in, so in a small corridor, the dagger user may hit, while the guy with the claymore will be seriously limited. Hitting the walls and items with your clumsy encumbered character should be noisy, and limit your stealth abilities...
Spears can be in, but it is not a matter of skill that keep them out, more a question of lazy developers to craft the appropriate animations.
To finish, your example of skills merging with the only 2 social skills is a bit opposed to your first idea of requiring 2 seperate skills to do the same thing : bashing people with cutting stuff. But I think it can also perfectly work with perk system : Lets have a general speechcraft skill with perks like : etiquette when talking to nobles; streetwise, with criminals and homelesses; Mercantile, to negociate stuff...
It is a classical RPG system structure : a set of general skills and specialisations. I would even say that it is a better one than a system with many completely parallel skills, even when some of them are obviously similar. Back to blades, how could you explain that a master swordman would not have been able to cut his meat with a knife? I prefere the idea of developping a basis, encompassing similar or intimately connected activities, with the ability to get some special focus on some of them.