Good to see this again!

Yes, it's the shortest chapter of the entire book.

We don’t get any clue why he doesn’t want to wear the uniform, let alone why that reason is strong enough to make Murtagh do something to make the mission harder.

I think it is because he doesn't like wearing the uniform of the guard he will be betraying soon. Whether that's worth leaving it behind... I don't know.

He does not use an invisibility spell. Maybe he doesn’t know one. But he also doesn’t use Maela to muffle whatever noises he could make, which is something we know he can do.

Yeah, he does know one, though I wonder if it would work very well here. Silencing himself would work very well, and he really should be doing it. I guess Paolini didn't have him use it because he thought it would make this scene tenser, but making Murtagh competent would do more for that.

He catches the guard, but the pike the guard was holding falls on the ground.

At least he took care not to hurt someone this time?

He watches a spider as he waits at one point, looking at it in disgust. Why he even notices a spider on the wall is a mystery to me.

Maybe he wants to make sure he knows where the spiders are? I can see him be on the lookout for them, at least.

Yeah, Paolini really liked to use sneaking scenes for this book, to the extent that he does get quite repetitive.

Also, there's an elipsis in the chapter title for some reason. It isn't necessary.

I think that one might be because Paolini thought it sounded tense (and it kind of does, but Murtagh is not going to have much trouble now).