Finley McLeod

The author intended for the Unsullied to be a superior fighting force to what Westeros can call together. That is what matters. Things like testosterone doesn't matter. Most of what Westeros can call together are not going to be in prime physical condition. Where as the Unsullied are all in fine physical fitness and are mentally ready for battle. The Dothraki riders are also fit and ready for battle.

The Freys could die without the family getting killed. The name Frey could be stricken off the list of nobility and its use forbidden. The family name dies but the family are not killed.

The scenes in the house of the undying were shown to let Dany know what is happening back home. It's to better prepare the young lady to assume her father's throne. Not that there will be a trial as that is unprecedented for a family feud and are usually settled through warfare. The Starks will have a throw down with the Lannisters and the Freys before Dany comes. The scenes serves only to inform Dany why the families fought and may help her find a way to hold Westeros together.