You know, since Impa is the Sage of Shadow, she could take some cues from the Shadow Temple's weaponry:
Neutral B: Gargoyle Fans:
These fans blow Link away in the temple, and these could be used to get the opponent away from the defensive bodyguard ninja.
While Sheik Fairs you off-stage, Impa will strategically get the opponent off her and strike when needed.
Side B: Floormaster
The first walking command grab.
Floormaster will crawl around and throws everybody he encounters behind him.
Think MechaKoopa X Yoshi Egg Launch
Up B: Hover Boots
Impa can now walk on air with the Hover Boots freely, but falls down after a time when she equips the Iron Boots.
These Iron Boots stick around for a while too, making her slower and making her fall faster, but also allowing her to unleash a powerful kick attack.
Down B: Invisible Walls and Invisible Spikes
BOOM. The opponent bashed against one of Impa's traps.
Impa's traps can only be seen when the Lens of Truth is activated, but otherwise, the traps are covered as if playing Invisible Smash!
Final Smash: Bongo Bongo
Impa plays her bongo and..
Obvious Final Smash, but she has more potential amirite?
Other:
Jab: Fire Eye
The familiar eye switch appears in front of Impa, hiding behind it.
When someone comes close, the eye spews fire.
When the eye is hit, it closes its eyelids and dissappears.
Forward Smash: Guillotine:
Impa summons a Guillotine to Smash opponents
Down Smash: Din's Fire:
Impa uses the original Din's Fire to light two torches at her sides.
When the torches hit the opponent, it has strong knockback and the classic Zelda theme plays.
Up Smash: Whirling Scyte:
Impa summons a big ferry wheel that whirl scytes quickly above her.
Some of these things are scraping the bottom of the barrel, but this is only a small part of Impa's legacy in Zelda.