A few things seem to have come up in the comments on the new book.
One is that there was little time spent talking about Laria's time acclimating to some of the changes she went through. To be honest, I had thought about writing on that, but I honestly didn't think people would be interested in reading it. Apparently that may have been a mistake, so I'm considering writing a short story, to go over the few weeks she and Will spent at the faire. If I do write it, (and I probably will) it will go up on my website, for free.
The other has to deal with Laria being able to bring something back, that William was not allowed to. Fel made the simple comment that 'she was carrying it, you weren't'. Which in this particular case is true. Now there has been some debate over this, and while I find it kinda cool that there are people into my writing enough to debate some of the aspects and plot points, there is actually more to it than was let on by Fel at that point.
I'm sorta debating how much I really want to go into it here, because I was thinking of using this as a minor plot point in Nikki's story, but yes, it is more complicated than people seem to be thinking. Yes, Laria was able to bring back an item that Will could not. Something that Will had not considered. Which may perhaps be a little surprising when you think how often he's trying to game the rules, but we all have our off days, and he had other things on his mind. Yes there are tech limits on what you can and can not bring into a world, but those limits are often about physics and the laws thereof.
Though not
always. There is the rule about champions bringing in items/devices/etc of excessive tech, or higher tech, so you've already seen. There also appears to be a rule about bringing devices of significantly higher tech as well, but its only been hinted at, I don't think you've seen it applied yet. The rule on champions has affected Will in subtle ways in the previous books that you may not have noticed, otherwise all of the gods would simply recruit champions from high tech worlds and have them come to theirs and build high tech wonders and death machines (and then there would be no low tech worlds, or developing worlds).
This is why you haven't seen Will use his engineering skills to 'do great things'.
Also, most god's champions can not travel through portals. Will is Fel's first champion with that ability. Eveon is also the first of her god's with that ability. Tantrus, has had several, but then he is a very powerful and old (by that sphere's standards) god. The ability to sense portals is very rare. Until Will showed up in Hiland, no one in the kingdom, or any adjoining ones, had it. So random people stumbling in, with specialty items is going to be a very hit or miss proposition.
And therefore, because of all of this, you are going to see some very byzantine plots and behaviors by the gods revolving around or involving portals. Sometimes it makes my head hurt just thinking about it.