black star has become very mature after he killed mifune and rarely ever fools around in a fight. and i said black star surpassed stein in hand to hand if you re read the chapter you can see stein says it himself right after bs kicked him the face. also speed equal only equalizes base speed unless stated otherwise.
Why would you doubt it? By nearly all accounts BS has shown himself to be foolish and arrogant, whereas Sasuke is cool and calculating. Do you think that Black Star could have thought on the level Sasuke did in the Deidara fight? Hell no.
Also, Black Star has not surpassed Stein. Stein only said that Black Star had the edge in physical force and possibly endurance. If you go back to that scene you'll see that Black Star wasn't even able to land a single direct hit on Stein. Mifune, of course, I will give you. And ohgodwhy has stated in the OP that speed is equal, regardless of techniques. Until he states otherwise, BS has lost his best and only advantage over Sasuke.
i agree sasuke has more of a wide range of different techniques but i wouldn't call them 'better'. kirin takes way to long to prep, there's no way he'd be able to get that off before bs attacks. and sasuke cutting through tsubaki is just lol. iirc sasuke only cut metal once and it was a random kunai while tsubaki has withstood multiple steel cutters at once.
And yes, better techniques. He has more at his disposal with clones, substitutions, lightning style techniques, a plethora of fire techniques, summons and genjutsu (if Blackstar makes eye contact he's dead), not to mention a little technique called Kirin, which has demonstrated more power than anything shown by nearly anyone in the entire Soul Eater series. Hell, Sasuke may simply be able to cut through Tsubaki's weaponry with a lightning-infused katana. As it stands, Blackstar is dying.
And when did Blackstar become hypersonic+? Last time I checked higher tier Soul Eater characters were on the mid-hypersonic range. With the level that Sasuke is at, he'd be at least supersonic+ at his current point. If BS were to go straight for the kill, he'd win, but if Sasuke gets the chance to activate Susano (which he may well just do from the start) then BS has no way of getting through. If it were their current, unrestricted forms it could go either way.
for black star being hypersonic; he was able to best mifune whom is hypersonic+ from blocking hypersonic sniper fire on multiple occasions and has dodged a detonated gun powder explosion point blank. at one point in their fight mifune couldn't even track black star's movements when he used zetseui.