This is a question with a few layers for sure.

We have to consider the function and prevalence of blades in general to answer it.

The basic thing to remember is that swords are intended to be functional weapons, and thus any ornament that makes them too heavy to be usable, or gets in the way of wielding them effectively within the sword martial arts the combatant practices, you can discard as pure fiction.

This of course excludes swords that are clearly only ceremonial, such as the Seven Branched Sword

With function in mind, there were certainly swords with decorated hilts, inlaid blades, and (especially) decorative scabbards/sheaths. This doesn't effect the utility of the sword, but lends the sword some extra grandeur, which was sometimes desirable to the wielder.

Some great examples of these are Napoleon's sword and the Tizona Sabre, which as you can see are highly decorative but also fully functional.

A discussion of the overall prevalence of swords is relevant here as well. This thread is quite good for that, particularly these two users replies: https://www.reddit.com/r/AskHistorians/comments/1u4j68/were_swords_as_common_in_medieval_times_as_books/

/u/sanpilou /u/Marclee1703

So, swords became more common overall after the 13th century, and even became accessible to the classes that would be soldiering. But an infantryman isn't likely to have an ostentatious, decorated sword, so while more swords were in production, the percentage of "unique/ornamental" swords would be fairly small.

Even some fairly famous swords sometimes lack in ornament, such as William Wallace's sword.

With all of that in mind, we can conclude that ornamental/unique swords existed, most often in the hands of nobility and the wealthy, but perhaps not at the volume shown in some fiction.

*This is my first post on here, and I'm definitely an amateur historian, so correct/inform me where if I'm off anywhere! *edited to include username pings for two of the more pertinent answers on the thread I linked.