Wodime's NP had already started to crack due to Rhongo even before he was stabbed (despite Rhongo being launched by a Lostbelt away), and Chaldea effectively judged it to be above his magecraft. Even then, Morgan has 12 of these.
Zeus did use his full power as far as I'm aware, apart from his most powerful authorities; also he himself judged Wodime as his equal, it'd be weird if he was only on par with some percentage of Zeus. Unless you mean that Zeus in LB5 wasn't fused with the other Olympians anymore, in which case yeah, he was past his prime.
It's fair that Morgan seems squishier than the other LB Kings with how she went down. Still, she was separated from her throne (and thus both Rhongo and the Fae's power), blind, not using any spell (as a top mage if she fueled the Fae's magical energy into barriers or healing the result would be crazy) and at death's door due to an angered Woodwose catching her by surprise. With her full arsenal she'd have no problem even against far more dangerous enemies.
But of course if you want to consider her without her throne it's an entirely different matter.
Overall she has been hyped up a lot for the whole chapter, to the point that imho it compensates her 'easy' end. Hearing about the Water Mirror was enough for Chaldea to deem her as the strongest LB King (sure it's Goredolf who said it, but Sherlock didn't contradict him), pretty much everyone kept praising her power and even before becoming queen she displayed crazy feats in magecraft.
Castoria also deemed she could have destroyed Cernunnos if she could use the Rhongos as well as Morgan. Even after she turned the Rhongos into the Holy Sword she couldn't destroy Cernunnos completely, so if her Holy Sword is comparable to the original Excalibur which destroyed Sefar, then that's further confirmation that we are talking about Zeus levels of power.