Character & World Building Fantasy Book Series Recommendations

I am looking for book recommendations for my husband and I to listen to (must be available as audiobook) together. He is not an avid reader and only read Ready Player One. He has listened to me read some books and enjoyed Quicksilver and Brimstone. We started the Eating Woods: Anathema series. The smuttier books like Ruthless Boys (and Zodiac Academy), The Female, Lights Out, etc are not what he enjoys as it is sometimes just sex for no reason and not always plot driven or made sense. I introduced him to Darren Shan's Vampire Assistant series and he LOVED it. I want to move forward with more challenging books now that I understand what elements in stories he enjoys the most.

Required Themes

• Medieval
• Sword/hand-weapon combat
• Character Development
  • through learning education, combat, magic, or other
  • not so much on the development of internal development of being a better person
• Similar to The Witcher (he played the games, did not read the books) & LOTR for fantasy
• Main character morally grey
  • cunning, witty, trickery to win or plot
    • think Kingfisher from Quicksilver, Mr. Tiny from Vampire Assistant, Zevander from Anathema
• Ideally more than 3 books in the series or multiple trilogies within a complete Series
• Series must be complete or will be complete by end of Feb
• Subplot romance (Quicksilver & Anathema) where it is not primary focus but romance can influence choices and decisions but not as intimately focused as ACOTAR
• Fiction

Preferences

• Medium or slow paced
• 500+ pages, at least 7 hours long but more is preferred
• More on the challenging side
• Dark, mysterious, adventurous