Swordmage Attack 1Booming Blade
A field of sound punishes your enemy if he tries to escape.
At-Will Arcane, Thunder, Weapon Standard Action Melee 1
Target: One creature
Attack: Intelligence vs. AC
Hit: 1[W] + Intelligence modifier damage, and if the target is adjacent to you at the start of its next turn and moves away during that turn, it takes 1d6 + Constitution modifier thunder damage. Increase damage to 2[W] + Intelligence modifier at 21st level.
The secondary damage is not a (W) so I am certain items like Iron Armbands of power will not boost it. However I am not so sure about the enhancement bonus of the weapon used in the attack and feats like "weapon focus" and "Eladrin Soldier."
A level 30 character will have a con mod of +10 (at best) its seems it needs to be getting an additonal boost somewhere to validate its use past early heroic. 1d6+10 damage is rather small at high levels.