Series numeration (Reluctant royals) from FantasticFiction.

New York City socialite and perpetual hot mess Portia Hobbs is tired of disappointing her family, friends, and--most importantly--herself. An apprenticeship with a struggling swordmaker in Scotland is a chance to use her expertise and discover what she's capable of. Turns out she excels at aggravating her gruff silver fox boss...when she's not having inappropriate fantasies about his sexy Scottish burr. Tavish McKenzie doesn't need a rich, spoiled American telling him how to run his armory...even if she is infuriatingly good at it. Tav tries to rebuff his apprentice--and his attraction to her--but when Portia accidentally discovers that he's the secret son of a duke, rough-around-the-edges Tav becomes her newest makeover project. Forging metal into weapons and armor is one thing, but when desire burns out of control and the media spotlight gets too hot to bear, can a commoner turned duke and his posh apprentice find lasting love?