The ending: doesn't seem to be quite right, somehow. It didn't come out 

the way >I wanted it to

You're right, the last part felt weak compared with the buildup before. How 
about showing Skuld learning her lesson that there are worse things than 
letting Keiichi and Belldandy  be together and being on Earth with her 
sisters. Such as losing Belldandy completely and STILL being stranded on 
Earth.
On another matter, the Lord never did say He forbade Belldandy to go to 
Earth. Just that she was underperforming.
And about that tree being used to make a mirror, I think its VERY unlikely 
even though that temple has been abandonded for years. Furniture makers 
just don't walk around the city outskirts looking for trees to use. They go 
to the forest.
Finally, I understand your reasons for using honored sister instead of the 
usual oneesama. Its ok, but it only conveys the respect Skuld has for her 
sister not the affection as well.��