He didn't tear it, he got shot in the leg.

It's definitely not.

Because Vandal Savage has the knife.

"Also, the one-eyed dude’s prophetic rambling makes me wonder if Eretria and Amberle are going to end up switching their story roles in The Elfstones Of Shannara when (and if) they finally get to Safehold."

Couldn't agree more. The very fact of Oliver having a son who he wanted to build a relationship with, and that boy having a mother that Oliver quite clearly had a relationship with at one point, would have been enough to give drama to Felicity and Oliver's current situation.
They didn't need to turn her into ridiculous…