Palutena's Utilt hits high enough that a shorthop Dair of Lucario has no hope of out-ranging it, but he does have aerials that will out speed it, and gets good results off of a grab if he tomahawks . As far as falling into it from above, if Dair will out-space it, it's a very precise distance an I cannot recreate it using my foot to play Palutena lol, might want to double check with a real person.
I do know a little about the Lucario matchup so I suppose I'll talk about that; one of my state's best players is a Lucario and I practice with him a fair amount.
Lucario doesn't have the strongest neutral in the world, and because of it, we actually do okay against him in neutral. Short hop fast fall fairs and jabs do a good job of keeping him honest. Auto reticule is somewhat dangerous to use, because depending on his percent, a aura sphere charged even a little bit will beat it out and we'll lose out in the damage department. He has fairly decent options to approach. Short hop double aerials mean that he really does have a worthwhile mixup on shield, since the second aerial will hit you if you shield drop, but he can easily land and grab you as well. Utilt is an option, but I don't use it much as it's painful to whiff and slower to come out than Lucario's aerials.
Once neutral ends, the matchup turns a bit sour. Lucario has fairly good both advantage and disadvantage states. Lucario has some decent capitalization off of his grabs, make sure to DI his Uthrow or else he'll get two aerials off on you at lower percents. When he's ready to kill, he has the option to use the charged aura sphere on your landing if he catches you airdodging or similar, and he can combo the hits on the charge into Usmash for a pretty reliable kill. The sphere charge also gives him crazy good coverage of our options on the ledge if he faces away from it. The ball covers standard get up and jump, and if you roll he can fire the sphere to catch you. He can also shield at any time, so while we can try to ledge hop a spaced fair or some such, we can get punished very hard for it as well since it's all too easy for him to jump out of shield and dair us for a stage spike on regrab. Aura Sphere is dangerous on our landing; unlike many reflectors, it can sneak in underneath a we're coming down. With a lot of aura, the grab portion of side-b will kill, so treat him like he has a kill throw and don't get grabbed.
On the defensive, Lucario has the fantastic option to wavebounce the aura sphere charge. This instantly reverses his momentum while still allowing him to air dodge at any time or shield when he hit's the ground. And of course if he catches you in it at a reasonable percent, you eat an Usmash. Bair through it if you see it, let him know we're not afraid of very active hitboxes. He also has a tremendous amount of control over his recovery and a huge distance to it when he's at higher percent. Predicting where he's going to land can be frustrating, and while it's not exactly scary, the hitbox on his Up-B keeps him relatively safe.
Now, all of this isn't the worst thing in the world. Like I said, we do have a (slightly) better neutral, so while he's got better options out of it, we can usually keep up with a Lucario of a similar skill level. The thing that makes this matchup negative in my opinion isn't any of the above, but getting the kill. This matchup gets harder and harder the longer Lucario lives, and Palutena is not good at ending a stock. Like many of Lucario's matchups, the fight is often going to come down to who gets the first kill. And that's usually going to be him. I feel like once he's at kill percents, it's beneficial to play a little more reckless to try and polish that stock off as soon as possible. Lucario with no aura is not likely to kill us easily and it gives us time to get a fair lead and make the next stock a little bit even. Killing a Lucario with tons of aura after you've lost a stock is a massively uphill battle. Whichever side of this matchup you're on, GET THE FIRST STOCK. It is so important.