I've been working on a character, Sword's Song, a blade dancery Fighter who uses two specially-crafted blades, a longsword that whistles and a shortsword that hums. They're lighter than usual, owing their fluted design, and meant to be wielded as a pair. She received them from a smithy for her assistance in repelling a goblin bandit party from ransacking the festival she'd been performing in, designed to give credit to the name she was given by the festivalgoers after watching her fight and hearing her steel sing in motion.

Song's Fluted Longsword is a basic Longsword at first glance, albeit one fluted and slightly less weighty, but it whistles with a high pitch as it picks up speed. It grants Advantage on Melee Attacks based on DEX, and a successful hit, unless a CON save is rolled against Song's CHA, will cause a round's worth of Deafening, with a -1 Penalty against Song's CHA each time this effect is successful that combat.

Song's Fluted Shortsword is a broad parrying shortblade, fluted like its longer counterpart, and designed in a particularly clever manner that allows the sword to hum in a low, strong vibratum as it is struck. Lighter because of its fluted craft, and being a defensive weapon, it grants Advantage on Acrobatics checks. I'm unsure how to fit in the humming effect of the sword, though.

Don't forget to make the longsword finesse. 

The shortsword looks like a common magic item.  The longsword looks like a rare one that requires attunement, or uncommon if it doesn't have finesse. 

Ah, okies. This is my first character... well, first anything DnD, really. x3

For the Shortsword, I was pondering something in a psuedo-parry. A CHA save against an incoming attack which causes the blade to start humming on success, deflecting the attack but becoming harder to control. Failure on the CHA save instead disarming the Shortsword from hand.

I like the flavor, but they're likely overpowered. Advantage is a powerful mechanic, usually acting like a bonus of between +3 and +5 depending on the AC range (some statistics involved). You'll notice that the highest flat bonus offered by any official magic weapon is +3, for some legendary weapons and artifacts. 

My suggestion would be to scrap advantage for the longsword, and give it a flat +1 bonus, while making the deafening ability limited in its number of uses, by giving it charges per day, or by making it a per-rest ability.

A shameless plug here, but I've also made a homebrew magic weapon that resonates as the flavor of your short sword suggests, it's been in moderation purgatory for a while:

Hmm... yeah, after watching some more Critical Role, I've come to understand how strong advantage is. Scrap the advantage... and for the deafening ability, what if it were friend-or-foe within a certain distance of the wielder? And also scrapping the advantage for the shortsword... and if the psuedo-charisma parry is too strong, what about a performance check with charges for bonus AC, with the condition of a failed performance roll resulting in dropping the thrumming shortsword, and the third charge use in a single combat allowing for a turn of +3 AC bonus, but guaranteed dropping the blade for the remainder of the fight at the start of your next turn?