It's not really the fact that it has super high priority, it's the fact that there IS ABSOLUTELY NO LANDING LAG WHATSOEVER.

Dolphin Slash in this game acts more like a combo (extender) tool more than anything now, with that, you can practically spam it if someone is in the air because you can't punish it like normal. But, I guess in turn, hit recovery stinks even more now. 'Least vertically.
The super high priority also makes it a fantastic anti-air too.

Dolphin Slash is a joke. That move should NOT be viable on stage. I hate how overbuffed Marth got.

Online more than Offline, but Top 5 is in reach. At least thats my experience. He is worse offline, but still a good option against campier charas as his fair destroys Missiles, Thunder Jolt and I think even Gale Boomerang. His main problem is his vertical recovery and he is somewhat easy to gimp. But DS really needs ending lag or less priority. Being able to spam DS or Dancing Blade and win without doing anything else is just lame. Even worse than Narutos Clones everywhere

But anyway, its funny how erveryone complained how bad Marth was before the patch and now everyone is mad because he is too good. I do get your point though.

I don't even think his vertical recovery is much of a problem now because his dair is so much better. A lot of characters can't even challenge it with their uairs.

Dolphin Slash has always been really good before the patch. It was probably pre-patch Marth's best attribute because of the platform mobility it gave him. I think it not being nerfed is just an oversight, mostly due to no Up-specials (but Mario's) having "true" landing-lag after going into free-fall. That's not bad for most recoveries, but for ones like Dolphin Slash (or Tiger Blade), it is silly because those moves become really combo-breakers for a free escape of pressure.

Marth also isn't overbuffed. He's has some good options similar to Melee Marth, but with shorter range. He's properly right around where he needs to be, just has a few dumb aspect; Dolphin Slash escapes/platform landing, Dancing Blade follow-ups are too fast/mashable, Counter has very low ending-lag to punish. I think that's what's mainly making him kind of difficult.

I agree with those "dumb aspects."

The dumb aspects make him unfun to fight against anyone who really abuses them.

When I do manage to get in Im afraid to try to pressure because of how free Swordryuken is.

Marth is so free man lol. The Fox MU is a joke now. You barely have to do anything to win with Marth. He's been incredibly dumbed down.

In all honesty, most MUs are like that agaisn't him right now, except for some special cases

Has anyone considered leaving DS as it is but removing it's knockback properties? If you do this, he can hit you with the attack, but you would immediately be able to counterattack because he barely moved you.

Would that make it too easy to edgeguard?

Marths should have to sweet spot the ledge anyways. I just got dolphin slashed like 8 times in a row on stage. It needs to get changed. Marth of all characters should not be campy and that's all I'm seeing online. It's sad. AsianPianist currently has the lamest Marth I've ever seen in my life. He literally dolphin slashes when you're not even close to him and side Bs like crazy. Marth's fsmash/tipper is also a bit ridiculous. Way too generous of a hitbox. I liked the way Marth played before because he required skill. DescendedSun will tell you that. All of these new Marths suck.

No character should have to sweetspot the ledge: going on stage should be viable as a mixup and should be doable against edgehogs.

Wouldn't a better way to reduce the spammablility of it be to reduce its priority and reduce its effectiveness as a combo breaker instead, coupled with a (maybe global) increase in specialfall landing lag?

I don't think the game should be balanced for online play. However, I think pretty much every up-spec needs landing lag. Marth's has always had so much that in brawl, using it as the combo breaker is a much riskier move. And in Melee, sweetpotting the ledge wasn't so much forced but just the best case situation.

Marth has always had to sweetspot. Why should that change?