Alchemy of Masques and Mirrors by Curtis Craddock
Born with a physical disability, no magical talent, and a precocious intellect, Princess Isabelle des Zephyrs has lived her life being underestimated by her family and her kingdom. The only person who appreciates her true self is Jean-Claude, the fatherly musketeer who had guarded her since birth.
All shall change, however, when an unlikely marriage proposal is offered, to the second son of a dying king in an empire collapsing into civil war.
But the last two women betrothed to this prince were murdered, and a sorcerer-assassin is bent on making Isabelle the third. Isabelle and Jean-Claude plunge into a great maze of prophecy, intrigue, and betrayal, where everyone wears masks of glamour and lies. Step by dangerous step, Isabelle must unravel the lies of her enemies and discovers a truth more perilous than any deception.