Ok so i took the 35mm scan, and ran it though photoshop with a simple levels adjustment, cliping the highlights 
And I get this result
Frame comepare here http://www.framecompare.com/image-compare/screenshotcomparison/K7P7NNNX
Obviously this is not scientific, it doesnt match exactly (due to the grain I think), but it shows how a simple levels transformation could be responsible for the TB saber looking that way. Its likely the super bright, high saturation lightsaber would have been simply clipped off through the telecine process.
As to why the Falcon lightsaber in the wide shot doesn’t do the same thing? You can compare the two sabers. Im Bens hut the glow is much brighter, almost as bright as the core where as the falcon saber the glow is much less bright and the saber has a harder edge. So where that levels transformation clips the soft glow in the hut, it doesnt affect the falcon saber in the same way.
The luke closeup is also different as the glow is almost invisible and the saber edges are very hard. Star wars is very inconsistent, there were probably several different ways they made the saber effects.
Here is the falcon shot with the exact same levels transformation applied. The glow is still present but its not hard clipped like the Bens hut shot.
I find this a lot more likely than the shots being completely rerendered for the TV release.