you can try it close to the end for romance could you make a class ascension and can you fix a bug next to the mage tower if you talk to the girl instead of the dog she will leave and that dog is bugged if you talk to it a certain way it freezes your game you should do a complete bug fix for the next update
You can buy a house plot if you find it in the western part of the Empire. There is a house to be bought inside Etrereburg that you can buy but not yet, it's done just need to finish quests and events there.
There are kingdoms in game which you will be able to join and maybe lead? I didn't finish that part yet but it's in progress
I can't really make a walkthrough that's up for the players/streamers. As for dual wield, you can do it if you learn the skill. There are "hidden" quests/events that will trigger if you done something before, like getting two party members or a questline that gives you something like the exotic vendor or the hidden treasure that you find around the map.
The best example is the Fast Travel from Bror Village. That's a village that has no connection with any place, but, if you do a questline, and do certian thing a wolf pack will attack the village, if you manage to defend it, you will get a new traveling route from there. There are a lot more exampless you just need to play and explore for yourself. As for the magic sword thing, there are currently 8 classes and 2 classes that can be "evolved" like paladin to blood knight if you find the secret place and do the ritual that evolves your paladin giving different spells.