Looking at Allomancy, you've mentioned that over time the power dilutes and each ability becomes less powerful. (for example a Tineye in Era 2 will generally be less powerful than one in Era 1) Does the same effect happen in Feruchemy as well? How would Feruchemy become less pure or diluted (other than Ferrings appearing)?
I have not gone as far with Feruchemy in that regard. I would say that if you're going to get a weakening of Feruchemy, which you're asking about, is the amount of stored attribute you get for lost attribute. There is decay there, you don't get a 1:1. Feruchemy generally I would say is not much weaker than it was before, a little bit but not much. This was done partially for narrative reasons. I wanted Allomancy... I wanted to back off a little on Allomancy and tell stories with it a little bit weaker. Again, mostly narrative reasons at this point. At this point on Scadrial, it's weakened about as much as it's going to because by this point people are having children that are more powerful because of the certain mixing. I'm not saying it's going up, I'm saying they have hit an equilibrium on Scadrial for the most part, at least in the Basin.