The character should be able to treat light blades as implements (via the Swordmage feature or apposite feat). Then, simply inferring from the rules:
Spiked Chain TrainingDDI
• Wielding a double weapon is like wielding a weapon in each hand. [...] The two ends of a double weapon can have different proficiency bonuses, damage, properties, and weapon groups. The weight and price entries represent the total for the weapon, rather than only one side.
• An enchanted double weapon gains all benefits of the enchantment on each end (even if one end would not normally qualify for the enchantment). This does not increase the frequency of use of any power possessed by the item; if you wield a double weapon with a daily power you can still only activate that power once per day.
[Multiclass Spiked Chain]
Prerequisite: Dex 13
Benefit: You gain proficiency with the spiked chain. You can treat the spiked chain as a double weapon. As a double weapon, each end of the spiked chain is a light blade and deals 2d4 damage. The primary end gains the stout property, and the secondary end gains the off-hand property.
Note to readers: spiked chains fall in the Flail weapon group. Is the Spiked Chain Training feat that makes them Light Blades too.
- being both ends of the spiked chain treated as light weapons,
- because of both ends of an enchanted double weapon gains the enchantment's properties,
- being light blades an implement for the character, and
- possessing the Dual Implement Spellcaster feat
the character may apply enhancement bonus damage to her implement arcane attacks from both ends of the double weapon.