It's getting exciting.

I have a few questions. One about these events specifically and a couple about this world in general.

Are these shuttles armed? If so, with what?

Hosts gain spirit by taking it from other hosts. When they gain this spirit, does it add to their maximum levels, or does it only stock up their supply with a finite amount of spirit meaning that it runs out and needs to be replenished by killing more hosts?

It mentioned in the history that the first core found exploded, taking out a mountain. Yet despite this latent energy in cores, there does not seem to be much concern about them being harnessed by anyone as strategic weapons (ie. nukes). Why is this? And, hypothetically, if I melted down a core so it stopped being crystalline, would its ability to hold energy cease and thus it release all its energy catastrophically?