It would be nice to have ItemMeta .setGlowEffect / hasGlowEffect.

Ideally this would use a custom NBT flag to prevent issues conflicting with removing enchantments. In other words "glowing" is its own state that is toggled on and off.

Disclaimer: I realize arbitrary item glow relies on what you could basically consider a client bug (or at least oversight)- but I feel like it's been that way for long enough we can rely on it for now.