Nothing stopping him from adding a line saying "btw, my bracers can give out awesome powers."
If he had a couple of thousand years, why take the risk making the bands now? And if they did exist, why not give them to a successor?
These bands of mourning legends sound too good to be true. Though I also don't know where the legends come from. Unlike a lot of the other mythology, there doesn't seem to be a source in the first trilogy. The Lord Ruler's bracers barely get a second though, IRRC.