Fiberglass weathers, but very little for the brief time periods it is exposed when fishing. Poor storage is usually the culprit. Fading/clouding very well illustrated in the pics above. . Also relatively inconsequencial considering the cost of utility priced fishing gear, which will usually long outlast the owner's interest in it. Put a rod away wet, store it with no ventilation and exposure to rapid temperature and humidity changes, and so on: it will show cosmetic changes and the composite itself be weakened. UV damage from sunlight, especially if accompanied by excess heat, is no friend to composites. Again, no big deal. Use it for what it is, and if it breaks, repair it or throw it out.
If you have one that hasn't suffered like the one shown, ordinary care and an ounce of prevention will do. A wax that offers UV protection--there are many household brands--is easy to apply now and then. Just be sure to remove it completely if the rod ever needs a new topcoat.
For classic brownish fiberglass (translucence depends on the prepreg, resin, and any coloring added) nothing beats spar varnish as an add-on layer of protection or rehab. Some makers chose opaque top-finishes, which conceal inconsequential blemishes. Realize, though, that the appearance of color in or on a rod may vary no matter what, simply because the wall thickness may vary down the taper.
viewtopic.php?f=6&t=18487&hilit=Fenwick+spiff