Over the years, some of the gen-one legendary weapons have undergone (documented) changes. However, as of last year or so, some of these items have "lost" their formerly on-use animations. At least the following weapons appear to be affected by this:
Bolt. At release, the lightning sound effect that now plays when drawing it was perpetual. This was later changed to what we observe ingame today, but when using a weapon skill, Bolt would also sometimes repeat parts of the drawing sound effect. This is no longer the case.
Quip. Used to spin randomly when drawing it and also when using weapon skills. Eventually received footfalls and a purple aura through a patch. Only the on-drawing spinning remains today, even though it was still functional when the aforementioned patch was released. The Wiki also contains wrong information in this regard.
Predator. The charr head below the rifle's muzzle exhales a fiery discharge when drawing it. In an update, Predator received both a new aura and footfalls. The discharge also used to occur when weapons skills were used (which it no longer does), contradicting the information provided on the Wiki yet again.
The Flameseeker Prophecies. In a patch, footfalls and a page-turning effect on the shield's book were added. The book's pages would turn when drawing the weapon and using weapon skills. The on-skill-use part is, to my knowledge, no longer functional.
I cannot provide video proof in this case because I do not know anyone who owns this item personally. However, I have observed it on both enemies and allies alike in all game modes over the past few years. Please let me know should my memory be failing me on this.
If some or all of these changes were intentional, a statement of confirmation would be most welcome. If not, then it is my hope they might be corrected in a future update. As of the submission of this post, I could not find an entry for anything resembling this matter on the known-issues tracker.