Making the 10,000+ year old have the maturity and personality of a middle school kid going through puberty wrecks the story. It makes it cliche, boring and cookie cutter. It ruins the well set up overpower character idea. He can't get what he wants through power, IE a normal and carefree life...
The amount of PTSD the MC is going to get from this event is the most traumatizing of any Harem MC. Angie and 'Liva love each other more than him.
Seriously though, the story is surprisingly well written at times. The scenario around killing given to Leon is better than most Shōnen. There isn't...
Students who treated him like shit and beat him up, vs the civilians of the (probably) largest city in the Kingdom. The attack is targeting everything and not just a single ship. He only has Partner and not Luxion's true body as a trump card since it is out of contact range.
The situation is...
This princess will pick a childhood fling/sweet heart/person over everyone else in the kingdom. That is a horrendous leader, why would anyone ever decide to follow her if they know she will pick her favorites at the cost of everything. She wasn't that stupid at first, but the plot needed her to...
It makes sense for a warrior who has killed hundreds-thousands or at least ordered it. People die.
Limiting the panacea to divine intervention via children's innocence is a decent narrative check on it's power. There has been a slow drip of a religion in the story based around a land god...
Learn to put on an act to catch the attention of a male... Something tells me that learning to access and use the the VR system of the imperial military is in the cards for our Dragon cadet on her way to catch the attention of a male.
The secret weapon of the kingdom is some ship that a rich guy used to get laid and shotgun married. It was used a few times then left in the barn until the apocalypse... and it still out specs all the non lost technology ships in the world...