These light tan deerskin gloves can be used with or without attunement.  

Not worn:  If a person within 30 feet and carrying a melee weapon speaks the command phrase, "En garde!" the gloves will spring to life.  A shadowy humanoid form will appear wearing the gloves, and will manifest a weapon identical to the one being carried by the speaker.  After a quick bow, the shadow figure will begin a sparring match with the speaker.  The gloves are always slightly better than the opponent they are sparring against.  For combat ignore all modifiers and roll a d20 for all attacks, both for and against the figure.  Attacks made by the gloves hit on a result of 16 or more; attacks against the gloves hit on a result of 18 or more. Successful hits against the gloves are answered with a loud, "Touché!". Hits made by the gloves cause 0 HP damage. The gloves will continue sparring for six rounds, or the contest is ended by any conditions that force an end to the duel, or the command "Fini!" is given.  The manifested weapon disappears, and gloves cannot be activated again until dawn the next day.  Completing the full six rounds of sparring gives the opponent a +1 to hit with the weapon they used until dawn the next day.

Worn, with attunement:  If holding a melee weapon, when the wearer speaks the command phrase, "En garde!" the gloves will spar with any creature that advances with any melee weapon.  The gloves are always slightly better than the opponent they are sparring against.  For combat ignore all modifiers and roll a d20 for all melee attacks for all combatants, both for and against.  Attacks made by the gloves hit on a result of 16 or more; melee attacks against the wearer of the gloves hit on a result of 18 or more.  Hits made on opponents cause 0 HP damage. The gloves will continue sparring until they are disarmed, or all opponents are disarmed, or the wearer takes any damage from any source.  The gloves cannot be activated again for 24 hours.

Notes: Combat, Outerwear, Handwear