I do not understand how are foci classified. Are they similar to enchanted stuff, where you have to recharge the enchantment intermittently? Or are they different cause they channel magic, rather than storing it and being changed by it?

Also, if foci are something totally different than enchanted stuff, then what will the Warden's swords be considered, because they can channel magic? Are the "cutting-through-enchantments" stuff a property of its enchanting, or do the enchantments only help in building up the anti-magic property of the swords? If the Warden's swords can be considered enchanted stuff, then so the magic get recharged when the Wardens channel magic through it?