Let's go back to your troll character. He doesn't start out with spellcasting skill, so there's got to be a mechanism for him to learn spellcasting. Are you suggesting that troll berserkers be able to cast spells right off the bat? What would that look like?
Once again. I DON'T MIND PRACTICING!
For a troll to learn spell casting he need to read N scrolls.
Right now he need pack of scrolls to the left and pack of kobolds to the right.
Read one scroll, smack one kobold. That's oddest way to learn spellcasting.
You could always start practising the skill early on, not leaving it till you reach zot.
I can't! Early on spellcasters are so weak, that attempt to practice fighting with
regular dungeon critters can end up with death.
And I'll repeat myself again - I'm practicing fighting as a mage only to gain hp.
Not to gain fighting skill itself.
If there was a way to pump max mana to some reasonably high value,
so virtual hp of a mage with guardian spirit will be on the comparable level of hp of
a fighter, than mage wouldn't need to practice fighting.
Try a different class/race combo. OR...suggest how Crawl could be improved. What would the ideal skill system look like?
IMO combat related skills should be trained in combat (only).
Without usage of exp pool. Or with faster training when exp pool is used.
Of course using high level skill to kill low level monster shouldn't train skill at all.
However lvl27 mage should be able to train fighting to, say, lvl13 or so, without need of exp pool.
I mean training in a dungeon on regular monsters.
Further training should be possible only with exp pool or on higher level monsters.
Things are difficult with non-combat skills. For example enchantments.
And especially spellcasting in general.
Probably just casting enchantment spell should train both enchantment and spellcasting.
But up to some level. Level 1 spells up to skill level 3, level 2 up to 5 or so, and so on.
If char have spellcasting 20 and enchantments 1, casting low level enchantments should
train enchantments without exp pool, but spellcasting should be trained (if turned on)
only if there is exp in the pool.
Low level mages won't be able to train some skill in a quiet corner because of hunger.
When hunger cost of spell will drop to zero, this spell won't train anything anyway.
If mage have some supply of food and decides to burn it for training enchantments, why prohibit this?
Armor skill, dodging, stealth, should be trained directly by current exp value of a monster you are dealing with.
Traps should probably provide exp value that depends on depth.
Btw weapon skills in adom are trained by usage only.
And level up value of non-combat skills that are not used at all is very small, and become 0 at some point without training.
In M&M skills leveling was performed by trainer. You pay money, trainer rises your skills
In IVAN everything is training by usage.
But there is harsh autoleveling system.
The stronger you get, the nastier monsters are generated in next level.