This power, as written is unclear.
Generally powers like this will specify two things.
- whether they target creatures or enemies (or allies)
- whether they target all creatures in the burst or a single creature.
This one does not specify either of those things. That means that it's up to your DM to interpret the intent of the power. There is a case to be made that it's a single target power (the singular use of "power"), but I'm pretty sure targets are referred to in the singular in multi target powers other places.
Given that it's a daily, standard action, item power. It's by no means out of bounds to take the broadest interpretation and say it targets all enemies in the burst.