Masterly
M'ASTERLY, adjective Formed or executed with superior skill; suitable to a master; most excellent; skillful; as a masterly design; a masterly performance; a masterly stroke of policy.
1. Imperious.
M'ASTERLY, adverb With the skill of a master.
Thou dost speak masterly
'I think it very masterly written, ' in Swift, is improper or unusual.