The 'persistent damage effect' that gets spoken against particularly vociferously on these boards is one where the spell lingers on the target, dealing damage. This can incredibly easily break the action economy, as well as result in a dramatic magnification of the practitioner's already typically superior offensive capabilities while circumventing their single glaring weakness (sustained activity is incredibly draining).
One where the spell enhances the weapon value of a mundane weapon, but where that enhanced weapon must then be used to attack normally, without the benefit of control bonuses from specializations and foci, on the other hand, is likely to result in an underpowered ability set (at least in my estimation).
Alternatively, you could simply have him take conventional spellcasting powers, entirely unmodified, have his attacks with 'imbued weapons' be resolved as normal spells, and then simply compel him on a regular basis when it would otherwise be to his advantage to attack from afar as other practitioners do. (ninja'd by Deadman)
A third option might be to represent his powers with Enchanted Items, which would give him the high weapon rating but comparatively unimpressive attack bonus that you would expect of a magically-imbued swordsman. The downside here being that his abilities would then be tied to particular weapons/objects.
