Spell Channeling is an item property that allows Magery spells to be cast without unequipping the Right and Left Hand equipment slots. It is always accompanied by a spell casting penalty of -1 (which does not count as an additional property), though this may be cancelled out if the item has a FCR bonus as well.
For example, an item displaying spell channeling with a FCR of -1 has a single property. A spell channeling item seemingly without the penalty has at least two properties. Keep this in mind when crafting magic items.
Spellbooks do not require spell channeling in order to stay equipped while casting. Wands always have this property.