I need to step in a little, I think. Cool down, Nepene and Windy.
I think it is premature to say that the Skaze have an influence in Bloodsealing. After all, there's no corollary to Seons in the Rose Empire, so it is very unfounded to say that Seons or Skaze are influencing the magic. They may not even be there.
Furthermore, I do agree that there's no evidence of Splinter based magic on Sel (they may exist, though, on planets that have no Shardic influence and only have a Splinter there). Because, one important part of Splinters is that they often have their own intent. The way one accesses the power must be line with the power's intent, and I highly imagine that a Splinter based magic system would involve you using the Splinter's intent instead of the Shard's--or the Splinter's interpretation of the Shard's intent. The actual mechanics of that doesn't really matter; all I'm saying is that invoking Splinters is probably not the simplest explanation.
A far simpler explanation instead of invoking Splinters is that different regions may have different methods of doing magic, say, in line with Dominion. The region breaking could be because magic on Sel changed after Devotion and Dominion Splintered. So, Dakhor may just be the Fjordell method of doing magic in line with Dominion's intent (and thus opening a conduit to the Dor), and Bloodsealing may be a different method of doing the same thing somewhere else. No Skaze required!
In fact, let me say that (because I have unposted audio) Bloodsealing is not a subset of Forgery. They are related, but different.
So, it's perfectly reasonable that Bloodsealing may be one manifestation of magic in line with Dominion's power. Nothing wrong with that at all. I think that was primarily what Windy was trying to get at there.
Also, Windy stated that very poorly, because Wyrn clearly has some future sight power. You are certainly right about that Nepene.
That is a much better way of phrasing the theory. It wasn't well stated it before, hence the confusion.