The blessing of Moses in Deut. 33:2
The Lord came from Sinai and dawned over them from Seir; he shone forth from Mount Paran.
This verse is almost unanimously understood to describe the revelation at Mount Sinai. But what's troubling me here is that the verse lumps together Sinai with Seir which is in Edom. While there has been a lot of disagreement about the true location of Mount Sinai, some scholars placing it in the Sinai peninsula and some in the Arabian peninsula near Midian, none so far have suggested that it is in Edomite territory (besides, just from reading the biblical narrative it becomes clear that only after moving away from Sinai did the Israelites reach the border of Edom). So why is Seir mentioned here alongside Sinai?
In the song of Deborah too this motif comes up,
When you, Lord, went out from Seir, when you marched from the land of Edom, the earth shook, the heavens poured, the clouds poured down water. The mountains quaked before the Lord, the One of Sinai, before the Lord, the God of Israel. (Judges 5:4-6)
Were the biblical writers confused about the location of Sinai? Why is Seir mentioned alongside Mt. Sinai in Moses' blessing and the song of Deborah?
This question is also found here, but there are no definite and conclusive answers. I'm looking for good answers that will resolve this problem either geographically or hermeneutically (I suspect that the latter is the only way to resolve the matter).