Sometimes, when competing in Trial of Style, the weapon enchant illusion will not change even though the transmog window shows it having been saved as changed.
For example, I’d done the “Crimson” theme contest and had “Sinwrath” on my weapon. The next contest was “Blue Skies” so I put the “Primal Air” illusion on my new weapon transmog. In the transmog window it moused-over as Primal Air, it even showed it on my char in the transmog window. But when getting on stage, it was still Sinwrath. The rest of my transmog choices stayed, but weapon enchants sometimes don’t. This happened multiple times at about a 50% occurrence rate. Even saving multiple times didn’t deter the issue from happening.