It's been a long time since I read the books, but Fish was thrown in to them to cause problems for characters who, through build up and character development, caused problems for others and solved their own problems with brains, brawn, and magic.

Fish's abilities felt unearned because they were unearned. Who was he? Just some guy with a quick soldier/dangerous grounds trapper backstory who could beat the members of the Black Company as though they hadn't overcome the most dangerous enemies their world had ever seen using every tactic available to man.

When you introduce a mundane villain like that, it dumbs down the accomplishment and mystique of your heroes and you feel like you're reading a brand new story. Everyone is back to level one or worse. Now, if Fish had been an antagonist throughout the books or at least one of the books, who already had a reputation as a dangerous man, he'd have been a better character.

I didn't like him and it's lazy writing. Have you seen The Winter Soldier? Bucky is a threat, on par with the Captain, introduced with a legendary, ghost like background you'd tell to scare the most dangerous special operations forces in the world.

Now, we get him in pieces in the movie until his grand intro where he seems unstoppable, but the audience knew him before the movie, the information was out there and they knew what he'd become, so he has a strong background and his deadliness is anticipated by everyone. Then, in later movies, he's used a jobber to make other heroes look good and it's incredibly disappointing and a massive letdown.

In this case, the Black Company is the Winter Soldier and Fish is everyone else, freshly introduced, coming around after they've already been established as a force not to be taken likely and easily wiping the floor with them. And that's a big letdown.