A question concerning wands

lillithj's post concerning wand-less Lucius reminded me of a rather strange inconsistency (one of many, yes, I know) in DH. Or maybe it isn't, I'm not quite sure.

In the first chapter - I think it's the first, but since I'm at work, I can't check with the book - during the meeting at Malfoy Manor, everybody is appalled when Voldemort orders Lucius to give him his wand. I think it says something like "he might as well have asked for Malfoy's arm". And everybody gasps in shock.
The way the others' reaction is described, borrowing a fellow wizard's wand is a breach of taboo (it strongly reminded me of the unthinkable act of touching another person's daemon in Pullman's Dark Materials).

On the other hand, Narcissa lends Draco her wand for the Battle of Hogwarts, and Hermione has no problems letting Harry use hers.

Apart from all that the-wand-chooses-the-wizard business, which means that you can use a wand that's not yours but it probably won't work for you the way your own does: If there is a taboo about using other people's wands, when exactly do wizards start feeling that way?

What do you people think?