If you have fluff cut it, but don't compromise your story for the sake of length.

How deep have you looked into the current state of publishing for epic fantasy? Most new authors are getting their start on Amazon using Kindle Unlimited -- sort of like Netflix for books -- and on that platform you get paid by the page. A 370k epic fantasy could be just what certain readers are looking for.

While I wouldn't totally discount what your editor is saying, it could be a good idea to find a place where the book at least ends in some fashion so you can share a "book" and then seek out some readers aligned with writers you think are in your same club. Find the Robin Hobb, Brandon Sanderson, Janny Wurts doorstopper readers. Facebook groups are a good place to start. Participate in the groups to gain some credibility, then ask if a few people would be interested in reading your book.

You want people who read for pleasure, not with the mind of an editor. These are the people who will, most importantly, pay for your eventual book.

The only feedback I would ask them to provide is, tell me where you put the book down, or where you were confused. If they do give feedback and 4 of 5 readers say the same thing, look at that issue. Otherwise its all subjective. If they finish the book and want more, then you're on the right track.

Working with editors is great but can be a real time and money suck, especially if the editor doesn't know the current marketplace.

Sure, it would be great to get published by Tor, but DAW just went out of business and Baen is hit or miss for epic fantasy, so there aren't many doors open anymore on the traditional route.

The only other advice I would give for fantasy is to work some element of progression into your plot. Doesn't have to be LitRPG, but progression fantasy is making crazy money right now.

The only reason you should listen to me is because I'm an SF writer who learned the editor lesson the hard way, especially concerning Amazon. Amazon pays monthly, rather than quarterly like publishers, and monthly income is nice. I also watch LitRPG writers and wish I had their audience. Ultimately, there's a ceiling on your success as a writer in any given genre. Fortunately I can pay my mortgage.

Good luck! 370k is a huge accomplishment. (You could also look at splitting the book up into smaller pieces, but a book that size could make a real splash from a first time author. The only problem is your follow-up, and fulfilling any promises about timelines to your readers.)

I have had to face what you are dealing with, but I am writing a very different sort of story and publishing as a serial, so it was much easier to break off "volume 1" earlier, I just had to find a place where the was enough of a shift in the story development that it made sense to put a small break there. Not so much as the end of a mini-story as the end of that stage of the story, if that makes sense?

I don't know if this will help you, my experience is different in several ways, but it's the best I have to offer right now.

I think the question is whether you want to make something sellable, something that pleases you, or something that pursues excellence. These things aren't mutually exclusive.

There's ways outside of the traditional publishing houses to publish things in the internet age, but you won't make much money, in all likelihood. That said, if the work can be improved by shortening, improve it. Rework it, focus it, and don't be afraid to toss old work aside when it has to be done. Think of it as a necessary stepping stone to making a better piece of art.