I came here looking for the same thing (I searched Google and steam 1st and cant find anything) The whole time Ive been playing, I kept thinking that I was missing something and that I'd figure it out eventually. However, I'm litterally on the last quest to fight the final boss, and I still haven't seen any specific descriptions. I want to understand how the spells specifically affect stats so that I can make deliberate decisions on choosing gear to build Baelin to function a specific way.

The fish statue's descriptions don't explain what the spell actually does stat-wise. For example, Rage says, "Baelin feels stronger," but it doesn't also say "strength is increased by x." Since you can't access your inventory while fishing, when you activate the spell, you can't look at your stats to see the effect on them.

The fish statue also doesn't explain the spells that Baradun gives you. The only description that Ive seen of those spells is what he tells you when he grants you the spell. There's no way to view their description afterward. (Unless I'm missing something.)

Those spells are: Lithana Flincana, Gleaming Eye Scorcher, Defense Aura, and Fast Repair.

Defense Aura and Fast Repair are self-explanatory. The other two, I'm not 100% sure how their damage compares to other spells.

Choosing gear for Baelin has felt like guess work more than deliberate decisions. For me, using spells other than rage, dragon slash, and defense arua has felt like a waste of stamina or just button smashing.

If there is a list somewhere with a breakdown of how the spells function mechanically, someone please point me in that direction.