I believe the WoL has hidden abilities that aren't known yet and also not hooked to the echo, I feel the echo is just a booster for our natural abilities and even without it because of how much we've been through we'd still be powerful enough to stand against most enemies.

a few places in the story point out that our character is an anomaly, mostly from hw scenes, even if somehow hydaelyn tricked us i'd bet our own inner being has been worked out enough to be its own beacon, which is what alot of our former enemies have been alluding to.