And I don't much see why in your mind dropping a Lady in there is conducive to anything. So great they throw around a ton of power and pyramids go down. Eb and Harry could have done that too, hell so could Odin...but clearly that would have just made the battle chaos worse and not in an effective way like Molly's one woman rave technique. If it was a simple matter of just brute force being necessary then they would have done it. As it stands they still had to rescue Maggie so a Lady blowing up everything in sight does nothing.
You are also supposing Lea did nothing BECAUSE of the lack of I guess firepower in your mind which is he only thing that constitutes a contribution. I think also because you don't view the Lords of the Outer Night as anything all that tough even though they clearly were...hell if Lea's ONLY contribution was 'Launching a surprise attack on the Lords of the Outer Night' that would have been of great help considering how strong they are...but she also did all those other things.
So fine the ramps are squishy...they had almost the entire army there! You mean to tell me that one Lady just makes them all insignificant? I think in the same way you see me overestimating Lea I think you are doing much the same with Lily or the ladies in general.
Several points to address.
1. No Harry and Eb cant do that, we've certainly seen Harry hit his limit well before the point of the fire wall Lilly threw out and whilst we don't have quite as clear a demonstration for Eb, but given we've never seen or heard of him doing anything like that without opportunity to pull a ritual i'm going to go with no he can't either. The closest we've seen was Harry tapping the Ley line earlier
They could certainly do some very big spells i'm sure that's true, but the really big stuff seriously drains them, they can't do a lot of it or at that kind of scale, not without prep time, Lily didn't even feel throwing her big spell around. And that wall of fire was hundreds of feet long and hot enough that Harry had serous issues blocking it even with winter backup. I can give the top handful of Ramps 1 step below the LotON, (like Adrienne) an "okay lets say they survive it due to foci benefits" pass since that seems to be "Harry Tier". But the rest are dead, deader, and even deader. Based on what it did to Fitz sword they won't even leave corpses.
2. Odin is a fairer point to raise, but the very fact that we never see him throwing around really big magical stuff, (the biggest thing he's done to date is the time trick in CD, and we don't really know how hard that is from a power PoV, it may well), makes it hard to judge his power. But given the lack of fireworks at CI i'm going with no he can't.
3. I understand the point about nuking not being useful at points in the battle. But that's why i picked the two examples i did. Immediately after Lea throws down the gem most of the ramps are still on the stands racing to get down, if she had that kind of power she could cut loose kill several percent of the total RC forces at the battle and have no friendly fire worries. And it's a level of blasting we know a lady can do. The second, when they're making their way to the pyramid base again includes a situation with no friendly fire potential, and againn included large numbers of Ramps tightly packed. Perfect area spell bait for someone who can hit an area that huge.
4. You still don't seem to get my point about the LotON. Hit the Merlin in the back with a very low power fireball when he doesn't know your going to attack him and he dies. Period. Doesn't matter that he's probably the most powerful mortal wizard alive, he's just as dead. Adrienne shows the same kind of "can't defend against what she doesn't see coming" problem in her duel with Harry. I'm sure a LotON is tougher even than a normal ramp physically. But their still going to go down if you hit them hard enough and anyone warden level or above can throw out spells many orders of magnitude above that required to kill a normal Ramp, so a group of LotOK? Not a challenge. IF you can catch the unawares as Lea did so they don't get to use all that awesome magical might to do anything about you smacking them down.
5. No i'm not judging Lea on her inability to nuke. I'm judging her on her inability to decisively effect the outcome of the battle once it's in progress through direct applied magic. Nuking is certainly the simplest and easiest method of doing that. But anything that akllows you to take large numbers of enemies out of the fight with very little effort will do.
Drop a Lady in lea's place and whilst saving Maggie is still not certain, (the battle will take time no mater what and thee are so many factors in play it's hard to predict specifics), the actual outcome of the battle, (the complete destruction of the RC), would have been assured. Don't get me wrong without the grey Council backing her up a Lady would have a serious time against the combined might of the 12 LotON and if you throw in the Red King i wouldn't want any Lady to try it without a bag full of Names. But with the mortal and birdman backup, no i don't think the RC could have survived the battle.
Lea never even comes close to demonstrating the kind of battle swinging power necessary to guarantee win that fight without using the ritual. A Lady given what we see could just by following harry around wipe out a goodly percentage of the RC's strength and given sufficient extra time, (how much depending on how much friendly fire she has to worry about), clean house with the whole lot of them.
That said i still ate Lea at a minimum equivalent to a LotON , i just don't think she compares with the Ladies.
6. I wouldn't say a Lady makes it insignificant, but depending on weather the ones in the stadium where there when harry reached the pyramid or came from the pyramid wiping them out wold take out anything from several percent, to potentially in excess of 10% of the total strength there. Throw in another swing whilst running to the pyramid afterwards and it's say anywhere from 10-20% of the total forces in 3 swings is doable. anything more than that comes down to having a sufficiently clear set of targets.
Based on the description of the setup at the pyramid when they first get there and the dimensions of the pyramid 4 swings would have wiped out >80% of the court in one go, (anywhere from 10,000-40,000 ramps depending on how you interpret some of Harry's descriptive text off the top of my head). Now i'm not suggesting that would have been the ideal thing to do. But it gives you an idea of what a Lady could do if they gave her a nice target, (and as noted we have a minimum 3 instances of such nice targets in the battle).