Gandalf in the 2nd Millennium of the Third Age

[Gordis]

Originally Posted by Ibrîniðilpathânezel

I think it might also be possible that during the siege at Weathertop, the WK operated by Sauron's "wisdom," driving his men (such as they are) from behind rather than leading the fray, and he simply never got to the front before the confrontation ended, or truly entered into direct combat with Gandalf. Perhaps he considered himself a much better tactician/strategist, and felt the strength of the others would be adequate to the situation while he directed their efforts.

The WK certainly operated by Sauron's "wisdom," so praised by Denethor, when he had orcs to spare as "cannon-fodder". But in all fairness, we don't have a single occasion when he had done the same to his fellow nazgul. Among the Nine, he was always at the forefront.

It was the WK who "swept away" the Rangers at the ford, it was the WK+2 others who guarded the borders of the Shire and Bree-Land against the possible attack by Elves or Rangers (RC).

At Weathertop there were five nazgul: two remained at the lip of the dell, three advanced on the being who wore the One Ring - which was, by the way, almost a sacrilege for a nazgul - see Letter 246:

Their weakness that the man's weapon was a thing that filled them with fear as an object of terror in their religious cult, by which they had been conditioned to treat one who wielded it with servility.

. When Frodo bared his perilous for the nazgul Barrow-blade, burning red in the Spirit World, two nazgul stopped, and it was only the WK who dared attack Frodo.

At the Ford of Bruinen, the WK was foremost across it, followed by two others, while the rest remained on the safe bank.
At the Pelennor, the WK was at the gates alone, while he could easily bring the rest of the nazgul with him. Same when he attacked Theoden (and that self-assurance had proved his undoing).

So, I don't see the WK remaining in the background while sending the weaker nazgul to fight Gandalf.

Also I don't see the "siege" of Weathertop as plain swordfight. I don't think the enemies even came into direct contact - likely it was a magick battle with lightnings etc., where only the WK was able to match Gandalf's magick (or attempt to). The objective of the nazgul was to drive Gandalf away, preventing him from joining the company with the Ring, not to kill him at all costs. This objective they had fulfilled. I think it was evident for the nazgul that they could only kill Gandalf at the cost of some of their own lives, and they were not ready to pay such price.