I found the bow for the Ranger relatively quickly (I couldn't complete the Secrets of the Dungeon – it's a completely insane quest), and it's only available to certain classes. ...

I completed everything for the Ranger. By the way, the classes are given quests of completely different difficulty levels; it's easiest for the Assassin, and probably the most difficult for the Ranger or Lich.

Everything I found was for Paladins. ...

Me too. NWC forces you to choose certain classes with artifacts.

By the way, they say that only a Druid can be a Grand Master of Agility. And it's even harder for him to deal damage than for a character in armor.... He's weak at the beginning, but when upgraded...

That's understandable, as well as bodybuilding, but he's weak in spells. He has 34, and the Priest has 42 or 43 (I don't remember)
P.S. there's also a bug with the armor of nature – it says that only a hero without armor can wear it, but I can put it on heroes with armor. But the spirit strength doesn't work