+3 Golden Quill

A golden quill which acts as an Arcane Focus, as if it were a wand. A removable golden sheath snaps satisfyingly onto a magic feather. The rarity of the magic feather determines the bonus of the item; the golden sheath is simply a conduit and has no power of its own. Changing the feather requires the work of a skilled artificer, with the same difficulty as a normal magic weapon upgrade. 

Common:  No bonus. A Hippogryph feather or equivalent, golden brown with a white tip.
Uncommon:  +1 bonus. The feather of an Enfield, a creature with the head of a fox and the wings of an eagle, or equivalent. It is striped in tones from fox red at the tip to white at the center and magenta near the base.
Rare:  +2 bonus. A molt feather from a mature Pseudodragon, or equivalent. The feather shimmers gold as if made of filigree. 
Very Rare : +3 bonus. A tip feather from an elder Coatl, or equivalent. The feather is an iridescent wash of rainbow hues that defy understanding. 

Notes: Bonus: Spell Attacks, Bonus: Spell Save DC