Sakura really doesn't need a weapon (unless we have some cool sword fighting). Enhanced strength, evasion tactics, Byakugo seal and medical ninjutsu is all she needs. Now after I finish my epic and get to the rewrite, I'll have Sakura doing that plus teleportation ala Kasumi from Dead or Alive, genjutsu that will be advanced and throw in a "reworked" version of Inner Sakura that inspired from other popular series.
Chakra Scalpel.
Yeah, I know, she doesn't really neeeeed a weapon...but.... Doesn't she, like, deserve one! And not just a dang chakra scalpel!!! (Ok, so I totally must have blocked out the ending of the manga because I don't remember that!)
She could have had something that was Tsunade's that was handed down to her at the end, or she could have something that was more historically correct. Like a tanto, a short knife traditionally used by women/samurai's wives for close quarters fighting.
Of course, any weapon would go with a power-up or outfit change, etc., none of which she overtly got in the manga. And none of it mattered in the end cause she was doomed to be stripped of all her previous shinobi prowess for the sake of SS and NH.
In a perfect NS-ending world, then Sakura would have a blade/tanto/shuriken that is inspired by one that Kushina had. It would be a nice tribute.