When player fishes up item with custom fishing rod

The only thing that's different about custom fishing rods from vanilla is durability and such. I know there is the "player fishes item" event trigger, but it doesn't detect what fishing rod you're using. And if you try detecting if the player has a fishing rod in mainhand or offhand, then you could be fishing with a normal fishing rod and having the custom one in the other hand unused and you would still get the bonus from the custom fishing rod even if you're not using it.

I searched everywhere and couldn't find anything like this, which is weird, what's the point of adding custom fishing rods if they aren't even that custom?

Also it would be nice to be able to change the item that gets fished up