True, I'm very much on board with balance changes that remove or rework content, but that is not everybody's cup of tea. Maybe I'll make a fork of Shattered on day to try out these things :)

I would think the mage would be, next to hunter, best suited for Fragile. Duelist tears.

I was thinking that it locks mage out of all non-staff weapons. Battlemage does not mind, but warlock loses a lot of options. They're probably both overall fine though. And right, duelist would lose an entire talent and some of their class identity, that is non-ideal.

I don't think it is quite the same, huntress is more defined by the bow, with the plant/dew interaction being kind of a secondary mechanic. I actually think she is the easiest class to do 9 challenges with, as you get a scaling ranged option for free. Regrowing grass is still extremely useful, and even warden gets some relevant utility by seeing through tall grass for trickshots. To hinder the other classes similarly to warrior, It'd have to be more like

• Mage: Remove scaling from wands
• Rogue/Cleric: Remove scaling from rings and artefacts
• Huntress: Remove ranged weapons and tall grass
• Duelist: Remove scaling from weapons

I don't think it is the warrior that needs to be changed, I'd rather see the challenges reworked. Badder Bosses and Hostile Champions are designed really well by adding challenge to the environment, instead of removing options from the player. Barren Lands, and Faith Is My Armor completely remove options (planting seeds, putting upgrades into armor), so those I'd replace. The other challenges seem fine to me. Some ideas for what could replace them:

• Curses: Curses are more common on weapons and armor (or even all are cursed?). Scroll of Remove Curse only weakens the curse on weapons/armor, another one is needed to fully remove it. Talisman trinket is disabled.
• Hostile Lands: A small percentage of tall grass and all naturally spawning plants are randomly replaced by vine lashers. These don't drop seeds when defeated. Could use the same logic as for the wandmaker quest to ensure there is still a safe path from floor entry to exit.
• Fragile: Equipment is destroyed upon unequipping (might be too harsh on mage?). Thrown weapons have lowered durability. Wands are destroyed on zero charges.

I think I'll switch to duelist for a breath of fresh air, weapon abilities might open up some other strategy than "pray for haste and a reach weapon".

Warrior definitely is the least interesting to play, but aside from challenges I don't think he is too weak. Being able to upgrade armor early and carry that +1 throughout the game always feels quite impactful.