I like those sandals, but, more importantly, you are drawn to them, so I think you ought to try them. I can see them with the borrowed navy dress because navy and black is a sophisticated combination. It might not be the outfit of your dreams, but it is a perfectly adequate fallback.
But, to my mind, here is where the fun starts. What would YOU put with those shoes for a dressy event? A long velvet skirt with an leather-trimmed top? A mid-length swishy silk skirt with an interesting banded top? If you can start thinking of possibilities that could work with these shoes, then those shoes could be the start of something. Once you have some images and silhouettes in mind, you are in a better position to look for YOUR items knowing you have the shoes waiting for their companion pieces. And, in the interval, you can also start figuring out how to use the shoes to turn some of your current pieces into dressy-casual outfits.
ETA: i just saw your thoughts about preferring a closed shoe. Perfect. Try the sandals anyway while checking out closed options. Think of those potential outfits. Would your oxfords with ribbon ties work with a velvet skirt and leather-trimmed top? How would the interesting banded top look with one of your summer skirts and the sandals? I guess my point is that the sandals can still be a smart buy if they work with other pieces in your current wardrobe and you have a possible closed shoe or boot that would work with your dressy capsule in fall and winter.
