Enchanting Equipment
Equipment is safe to be enchanted up to +4. After +4 there is a rising chance you will break the equipment.
Weapons that are +5 to +20 gain glows. They go from light to heavy glows. Levels 5, 6, 7 are clear, 8, 9, 10 are blue, 11, 12 are purple, and 13 through 20 are red.
Disenchanting Equipment
It is possible to retrieve some cubes from broken and enchanted equipment. You do this by "reducing" or disenchanting the equipment.
To reduce you need a reducing toolset and a reducing cube of the appropriate rank. When you reduce a piece of equipment the equipment and the reducing cube are consumed. The toolset is not consumed. Reducing is done through the combination window like enchanting is done.
The number of cubes you get back from a reduction is based upon the enchant level of the item being reduced. You get roughly 1/2 of the cubes back. So a +4 will usually give 2 around cubes back.