IMO right now, only top tier nerf needed is some kind of sheik needle nerd, personally I'd like to see the range on those needles nerfed, don't like how they excert pressure from so goddamn far away
Other than that I think what the game needs is some buffs for the low-tiers, like the goddess, give Palutena super speed in default and she'd be good to go, Zelda needs some major changes, Samus needs a fastfall and less lag on missiles. It'd be great if we could have the low tiers also be veritable mid tiers like the majority of the cast.
Anyway about Swordie's moveset, I agree on Shuriken of Light, it's just a great and simple move. Don't really see how you could prefer any of the others.
I prefer slash launcher for the side special, it's faster than airborne assault on start if you release early, thus you can use it to recover horizontally without giving the opponent a chance to telegraph and punish if the distance is small, if you need to charge it, well it's still faster than aerial assault. It deals less damage for sure, thus its more viable for the opponent to jump out and take the hit in order to cause swordie to fall to his death, but its also harder to do so because of its speed and the way you can time your release, plus if the opponent does take the hit to cause an SD you don't fall backwards a small distance like you do with aerial assault, also makin it harder to gimp. Lastly, its more useful as an attack than aerial assault, I find there are actually times when I can land it or use it to extent combos. I just feel that overall slash launcher is slightly better.
I agree whole heartedly on hero's spin, it's just way way better than the others, I used to go with the back in the stone thingy or whatever its called, once I switched I realized I was being ******** using that mediocre attack. It really is a great kill option too, means you never have to use the crappy dsmash, the fact that it hits instantly on both sides.. combined with the sheer power of it.. its just yummy yum and way outshines the other options.
As for down special.. I dunno, I prefer counter I think, its neat for punishing holes in combos and deadly if you make a read on high percents. But I do like how power thrust can punish opponents eager to juggle and how it acts as a faster (not initially but it reaches further away faster than dash attack) and longer ranged dash attack. I find that it, similarly to counter can be used once to thrice a game before it gets predictable. Reflect is good for some matchups of course, but I only pick it against opponents with strong chargeable projectiles.