Arcane Implement Proficiency is a heroic tier feat available to characters with any arcane class.
A character with the Arcane Implement Proficiency chooses an implement group used by any arcane class. (I.E: Swordmages's light and heavy blades) The character can use that type of implement for any arcane implement power.[AP:124][U :12/2009]
The December 2009 update removed Arcane Implement Proficiency's requirement that the chosen implement group be used by an arcane class other than the character's own, since the requirement unduly limited multiclassed characters.