Reach Weapon, One-Handed

[Malachei]

In order to support a build similar to this, I'd like to give them the ability to wield a reach weapon one-handed.

I think a feat is the best way to achieve this, and call it

Hoplite
Prerequisites: BAB +1, Shield Wall
Benefit: You can wield a longspear in one hand when wielding a shield in the other. You cannot also use a shield bash at the same time when you're attacking with your longspear on your turn.



The idea is mainly to offer mechanical support for low-level NPC hoplites, but of course I have to look at potential abuse by characters, as well.

While the hoplites can shield-bash or attack with longspear on an AoO, they cannot use two-weapon fighting to attack with longspear and shield bash in a full-attack action.

My questions:

Do you see problems with this feat?

Is there an official or other source for another way to achieve this (without changing size, etc.)?