Throwing weapons would be neat, but probably a bit of a headache to balance. Throwing axes and wands working with marksman skills is kind of an awkward concept, but still kind of awesome sounding. Probably would need them to not be quite as effective with marksman skills as bows and xbows to balance properly. However, I don't think spears should work with marksman skills, but with Scoundrel and Warfare ones. So basically I see it:
Throwing Axes: Warfare + Marskman hybrid weapon (lower damage than standard axes)
Throwing Knives: Marksman + Scoundrel compatible (lower damage than daggers, but still can backstab and more versatile)
Wands: Mage + Marksman compatible, but Marksman skills aren't quite as effective with wands (if necessary, stat split obviously already has a cost)
Staves: Mage + Warfare compatible
Spears: Warfare + Scoundrel skills
Possibly I could see throwing axes and spears having throw skills that make you actually lose the weapon and have it appear at the enemy's feet, but that would involve some consistency issues, given there's already a throwing knife skill that automatically returns the weapon to your hands (somehow).