Okay, I don't have the PH3, so assume it's not a factor.
What is this "Versatile Expertise" that everyone's talking about?
D&D Compendium said:Versatile Expertise
Heroic Tier
Benefit: Choose a weapon group and an implement type. You gain a +1 feat bonus to attack rolls both when using a weapon from the chosen group and when using an implement of the chosen type. The bonus increases to +2 at 15th level and +3 at 25th level.
Special: You can take this feat more than once. Each time you take this feat, choose a different weapon group and a different implement type.
First published in Player's Handbook 3.
The thing is that most weapons can be used as implements by some class, and it doesn't have the weapon/implement attack restrictions of erratad weapon/implement expertise, so a stereotypical swordmage would take versatile expertise (heavy blades & light blades).