(Is a horse more agile than a monkey? ~but who would win the 100 yard dash?)
Agility and Speed aren't entirely the same thing, instead of merging them, I would rather have that they make them be more important.
On a similar note:
Strength: Greatsword (2 handers), Mauls, Large Mauls (2 handers), Marksman (with crossbow), Polearms
Agility: Sword, Acrobatics, Athletics, Stealth, Concealed Weapons (daggers and thrown small weapons), Theft (lockpicking, pickpocket, and shoplifting)
Endurance: Hand to Hand, Equestrian, Shield, Outdoorsman, Climbing, Chain Weapons
Personality: Streetwise, Etiquette, Mercantile, Diplomacy
Willpower: Illusion, Enchanting, Destruction, Dynamism (replaces alteration, includes force type powers like telekinesis), Thaumaturgy (religious magic)
Intelligence: Mysticism, Daedric (replaces Conjuration), Necromancy, Alchemy, Medical
I think this an awesome suggestion, I just still feel that there's something which Agility and Speed can govern, like for example speed of attack, or damage of a sprint attack, provided such a thing is made.