Of course it's not all in the numbers.
However, before you could leverage a book that came out literally 1 month ago, Fangs was clearly outclassing it for a good long time. We had no context. There were very minimal crafting rules to speak of. There was very little guidance that says any of this. Andrew has not mentioned his design philosophy, as I live a couple thousand miles from him, don't attend conventions on that coast, and never got to sit down a play it before I got the book. There is no context. I'm left with pulling 35 years of gaming experience and board questions and 10 years in a career analyzing things to try and tease out intent.
I have checked out dvergar engineering, creature reliquary, realm ores, non-standard metas and infuse. those things, besides being factored into my spreadsheet (note, I compared QR rating), are also irrelevant because we are discussing armor penetration. There is still plenty of difference there, as you don't have to have weapons with a fixed Pierce, while Fangs is very predictable.
The chart's intent is to give some folks who have questions about it (myself, at least a couple other people) an idea of the impact of pierce, what it is at particular points, and if it makes sense to include it with Amplify or not. It resolves a question my group had about it.
Before Denizens, Unarmed was clearly more damaging - largely because of the existence of Fangs and Blood Wolf. The only character that gets Fangs is ALSO the one that gets Blood Wolf. Fangs gives you a very strong scaling two hander. Blood wolf gives you at least QR5 worth of weapon and armor, on top of size +2 and quadruped and a self heal. It so strongly outshone everything because of the lack of existence of an alternative.
At least now it's possible, and it tells the Norn who is looking to make sure all his players have a chance to shine what has to happen at that point. If you have someone who wants to be a damage monster and is not a Wolfen Ulfhednar, you must provide QR 75% weapon opportunities for him. It doesn't solve movement, it doesn't solve armor, but that's outside of the scope.
If you don't want to be bound to that, you can swap mechanics and use Pierce being Amplified off of weapons. Myself, I prefer this mechanic for a number of reasons - it's consistent, it's simpler, it's clearer, it's clearly balanced against Fangs, it makes resource gathering useful and an important advantage, and it makes the Blacksmith and the opportunity to get QR 75% a special thing. A reward for excellent activity, a singular niche that can't be just had for a rune by one guy. It must be invested in, one way or the other.
lets also not forget it's not like the Ulfhednar can't benefit as well - I read Dvergar Engineering well enough to note the "use your accessory while shapeshifted" for QR 2. Poof, I can get lots and lots of versatility.
Certainly, with RGS you get more than two play styles, and by no means am I trying to look at it with realism. I've called FOTN "Anime Vikings" more than once and I hold to that. That is not the point. I don't think it needs to be realistic, just that it should be comparable. The unit of measure, in this case, is a Rune. What can be done with that one rune. If it's not comparable, then there is clearly a better choice in the situation, and thus that needs to be defined.
edit: oops, a word.