Most of it looks good. I do wonder why her Control (Skis and Snowboards) is so low for an extreme sports fanatic.
Mostly because it didn't occur to me that I needed
Control skills for those until I was almost out of XP and happened to notice that Uller is statted with Control (Skis) 5. I was thinking mainly in terms of Athletics for sports. (Realistically, she should probably have at least minimal points in Control (Automobile) too.)
don't understand the logic in how they decided which Abilities require specialties and which don't.)
Do I understand the concept correctly when I ask if Amy was some sort of sports star or professional athlete prior to her Visitation?
More of an enthusiastic amateur, really, although she might have developed some amount of notoriety if that suits the story (especially once her Epic Dexterity/Charisma kicked in).
What is the Armor of Achilles effect?
The Armor of Achilles is a relic used by Victor Fingers (page 308 in the Hero book). It greatly augments the Damage Conversion knack. (It does seem a bit powerful, so if you'd rather disallow it I'd understand.)
Can you explain more about her wolf? It seems to be an important part of her character. Also, are you planning to upgrade the wolf at some point? I'm a bit concerned that her wolf might not be able to survive at this level of play without some sort of enhancement.
I'm working on the details, but the gist is that she has a bond with wolves due to being a Scion of the god of winter and hunting. The plan was to use Jotunblut 6 (Hounds of War) to turn it nemean if it was meant to accomplish anything.
Even a nemean wolf is pretty much a joke in high-end demigod combat, but unless I'm missing something, that's true of absolutely anything you can buy with the Creature Birthright (same goes for Followers). There's a reason she's got a Relic to bring it back to life.
All that said, I might redo the sheet to get her Ability scores into a more sensible spread. ...Especially since I only just noticed that Beowulf has Teaching Prodigy, which might change things just a bit.