The part in the ask was just a joke, and for most borrowers, echolocation wouldn’t be a useful ability, as they can all see in the dark from their time living in the walls. The Grace allowed them to adapt to the life they live quickly.
This would be a very useful ability for a blind borrower, along with a few others that also enhance senses.
February 7th excerpt:
“I’m gonna be feeling that one in the morning,” Dean gasped out as he managed to finally sit up, letting his arms fall limply across his legs. He coughed, trying to clear up his throat.
That was when he finally realized that he was sitting in a hand, and a familiar one at that. He twisted around, staring straight up at the human that was looking at them both. He gave Jacob a wry grin. “Guess we coulda used Godzilla with us this time,” Dean tried to joke.
Brothers Apart 