Not over thinking, a good question. What Fel suggested is probably the best answer. The weapons and such count as Schizo Tech. To quote TV Tropes: " There's generally no rhyme or reason for which technologies are anachronistically present besides the Rule Of Cool. Sometimes these may be leftovers from a lost technological civilization, or perhaps it could be that science developed along a different path than ours, allowing for more advanced technology in one field, while stagnating in others, but most of the time there is no explanation whatsoever for the bizarre mix of medieval and futuristic."
The weapons themselves aren't that important, what is is how people try to deal with certain plot elements at the time. We are dealing with characters that are larger than life, so true realism isn't really that important.
I am going to suggest a tentative region to region sort of concept. I am a little worried about the size and scope but on the same token, it can help prevent clusters around a single concept or characters.
The Kingdom of the East : Jack Shade and Tortsy are currently in the city, Jarakahl and Myrnodyn will start their journeys from one of the villages in this region. Maybe place Konrad Alyxander here as well for the time being.
The Southern Cross : Grandmaster Karsikan Banrae and Rameses Abraxas are on the hunt for Asmodeus since the fugitive has been rumored to be in the region. They were hired by Palonis. We can assume that there will be a rivalry as the plot progresses. I'll suggest that Vay starts out here.
The Western Confederacy- Knives, Ossa, Miru this will be your time to shine. Chopstick's region tends to have less in terms of oversized monsters and the such. Meanwhile Thomas and Eros are on a hunt of their own. Receiving orders from a group that calls itself Luna, they are to hunt down a strange bird-like woman (Harpy).
The Northern Wastelands-Fel and Krestal are on the war path with Colie and King Weavel. They plan on spying on Megane during a party that he is throwing with local nobles in order to muster more support for his weak regime. Meanwhile, Zypher is lost in the near by woods and will either have to join with Fel and his allies or face execution.
