Well I am sure you can always console the change, but for the tougher monsters you are really limiting your party. Why do you want to not get any more HP after 3rd?
Are fights with tougher monsters mandatory? I have never went though the full game. I prefer when it's possible to bring down humanoids and similar creatures with a good critical hit.
Well at the lower level of the temple you can get critters that can cast high level fireballs, have 4+ attacks around, and who may do 20-50 damage PER hit. Your choice but if you really want to gimp your characters, you can decide not to wear armor, low con to the group, or not have max HP per level for your characters. Again whatever works for you, but be prepared for a possible TPK- total party kill-in some of the battles. Good luck.
Actually, I want to make armour more effective. I want to mod the game to be a bit more realistic, not to create artificial challenge.
There is no making 3.5 more realistic; it was never designed with realism in mind. Also, the only way that makes armour more effective is if you also make armour reduce damage taken rather than making you harder to hit; by level 10, getting hit is going to be a pretty regular occurrence, and what would be a manageable fight by default rules would be made practically impossible short of some very lucky rolls of the dice - and if the party gets hit by a fireball towards the end of the game, it's an all but guaranteed TPK.
What it was designed for is irrelevant to me. What the engine is capable for is. For example in Infinity Engine engine games there's a HP increase table for each class. Is there anything like that in ToEE? It's because there's no AC progression. Which is kinda silly. If effectiveness of attack increases from level to level, effectiveness of defence should increase too. Sounds like it would be... *puts on shades* ...the end of the game. YEEAAAAHH!!!
