Okay before I say anything else, I want to say how glad I am that your recovery and getting back onto the stage from the ledge is so much better than where it was when I first started yelling at you. You're more patient, you're saving your jumps, you're making better decisions, and you're getting off the ledge in different ways.
I'm upset he didn't die at 1:26
Fsmash from nair will work if you stutterstep forward. However, that is more of a read for his fsmash. If he stays shielding you miss tipper fsmash on shield and lose all safety you might have had from shield push.
Dtilt from nair isn't that great vs Lucario. Dtilt from non-tippered fair is still good though.
The problem is nair is so long that if it's spaced, even without the backing up from his fsmash, dtilt shouldn't hit people. If you hit with non-tippered nair that's something different. But, why would you be hitting with non-tipper nair?
If you think the fsmash is coming at you OoS from your nair, walk forward a little, shield, and then either DB OoS or grab him. If he charges the fsmash more, then DS during his charge time to get 1.5x knockback. If he stays shielding (decides not to fsmash), just grab him.
Another option, although this is dependent on him fsmashing, is to just dash forward a little bit and DB. Of course, if he decides not to fsmash then you're DBing into a shield, poorly spaced at that, which is never good.
More ftilt in general.
Watch your full hops. They get you fair'd and AS'd a fair bit.
If you nair and he rolls behind you, make sure you start drifting forward so you don't continue back into your opponent.
Good lord, use dsmash sometime, it's a great move.
If Lucario fsmashes and you manage to be in the air above it, don't FF fair. If you do it too early you get hit by fsmash and if you're even a little bit too late you get PS'd (see: 0:30). Instead, you want to just nair. Fair starts above your head and arcs down which is why you need to FF it to hit someone on the ground safely. Nair's angle starts low so it will automatically hit a character at an angle of depression compared to you with no waiting (again, see: 0:30). Keep in mind that Marth sticks his hand out farther for this so you don't want to FF here. If you do you get hit (see: the second fsmash at 5:31/5:32. You were out of nair range for the first one).
Your fsmashes when he's at kill %s are pretty telegraphed. You know a Marth is going to fsmash when he slowly starts walking away from another character. Instead, try walking away then dashing back for a grab. It works almost every time.
While you've gotten extremely better on the ledge, you're still not making full use out of your options. Ledge jump-> DB1 to control your height->aerial/AD/counter/DB/double jump is a way to give you a lot of options from one action. Also, ledge jump backwards (into possibly DJ if necessary) into PC when the platform is offstage and behind you gives you a way out of a terrible situation. As long as you watch Lucario's Aura Sphere (which you just counter) you should be safe in getting to the platform. Keep in mind, Lucario is depressingly slow (see: 4:25)
Also, my favorite ledge trick, jump from the ledge into someone (DJ if necessary) and don't use and aerial or AD. Instead mash jump so you footstool over them. This works especially well on SV since you can wait until the platform is in a decent position for you to land safely.
Learn when to recognize when the 4th hit of DB will miss. Or just do DB the correct way and it won't matter.
You seemed to have gotten flustered a little bit after you got hit by fsmash at 5:31/2 until you died. Your recovery wasn't anything like what is has been. Just relax and focus on getting to the ledge (that uair from your jump you did when you could have just DS'd to safety jumps out). Remember, your #1 priority is getting to the ledge. Damage to your opponent is nice if you can get it, but don't worry about that. Keep your aerials unused unless it's necessary/your opponent lets you hit them for free.
I'm upset that utilt didn't kill @ 6:41
Game 2 you just seemed flustered overall. Too many fsmashes, bad recoveries/ledge options. You weren't landing that well, ran into attacks a lot, etc.
You land a lot with fair behind your opponent when uair would hit them. Fix that.
That dtilt at 8:53 was beautiful.
madmadmadmadmadmadmadmadmadmadmadmadmadmadmadmad @ your SD spikes. Especially mad that the second one was brilliantly done except the death part what you could have killed him with FFbair
15:28 Even if that had connected it would have been the weak hit. Back side of nair or bair were far better/safer/more likely options.
15:40 DSMASH WOULD HAVE WON!!! Also DS
15:47 Again, he was guaranteed dead almost any option he took from the ledge. Dsmash/DS instead of grab.
15:53 Noooo, ledge drop, jump, nair through him so the backside hits him back out//kills
I need to talk to you about nair follow-ups sometime this week.