Because to do so is to deny an entire category of implement to every single Small character capable of using staffs?
That's not the implement's problem. That's a small character problem, which needs its own fix.
This how I treat staffs (and interpret the rules):
- When used as an implement, Weapon Skill Focus does not apply.
- When used as a weapon, weapon proficiency and weapon focus applies.
The problem is, weapon focus *does* apply to implement powers (at least per Character Builder). However, when it applies seems to be a question of debate. There are 2 main categories of opinions:
1. Weapon focus applies if you use the staff as a weapon (two hands) using a weapon or implement power.
2. Weapon focus applies regardless of how you use the staff (one or two hands), when using an implement power.
Actually, there is no reason to believe you need to use two hands for a full blade or mordenkrad when using them as an implement.
By this token, Swordmage Warding should grant a +3 bonus for two-handed weapon users because you're not really using your off hand for a two-handed weapon, it's just an implement.