Champions without magical disciplines

I don't think so. If you have a shard of a particular type I think there is a chance he will get that trait when leveling up

Would that only be for Champions without disciplines or also for the rest of champions? I can certainly say that I have never seen a Champion developing new elemental affinity.

I am looking at the code for Air1 vs Air2. It seems that Air1 has no tag for probability while Air2 is rated as common. Hard to say what the deal is here. 

<AbilityBonus InternalName="Air1Ability">
<AbilityBonusType>Champion_Spellbook</AbilityBonusType>
<AbilityBonusType>Unit_Spell_Rank</AbilityBonusType>
<SpellbookType>Air</SpellbookType>
<AbilityBonusOption InternalName="Air1">
<DisplayName>Air Apprentice</DisplayName>
<Description>Allows the unit to cast rank 1 Air spells like Evade and Haste</Description>
<Icon>Ability_AirApprentice_Icon.png</Icon>
<GameModifier>
<ModType>Unit</ModType>
<Provides>Allows the unit to cast rank 1 Air spells like Evade and Haste</Provides>
</GameModifier>
<Cost>1</Cost>
<IsCombatAbility>1</IsCombatAbility>
<SpellbookRank>1</SpellbookRank>
<AIData AIPersonality="AI_General">
<AIPriority>5</AIPriority>
</AIData>
</AbilityBonusOption>
</AbilityBonus>
<AbilityBonus InternalName="Air2Ability">
<AbilityBonusType>Champion_Spellbook</AbilityBonusType>
<AbilityBonusType>Unit_Level</AbilityBonusType>
<AbilityBonusType>Unit_Spell_Rank</AbilityBonusType>
<SpellbookType>Air</SpellbookType>
<AbilityBonusOption InternalName="Air2">
<DisplayName>Air Disciple</DisplayName>
<Description>Allows the unit to cast rank 2 Air spells like Aura of Grace and Guardian Wind</Description>
<Icon>Ability_AirDisciple_Icon.png</Icon>
<GameModifier>
<ModType>Unit</ModType>
<Provides>Allows the unit to cast rank 2 Air spells like Aura of Grace and Guardian Wind</Provides>
</GameModifier>
<Cost>1</Cost>
<IsCombatAbility>1</IsCombatAbility>
<Likelihood>450</Likelihood>
<RarityDisplay>Common</RarityDisplay>
<SpellbookRank>2</SpellbookRank>
<Prereq>
<Type>UnitStat</Type>
<Attribute>UnitStat_Level</Attribute>
<Value>3</Value>
</Prereq>
<Prereq>
<Type>AbilityBonusOption</Type>
<Target>Unit</Target>
<Attribute>Air1</Attribute>
</Prereq>
<AIData AIPersonality="AI_General">
<AIPriority>5</AIPriority>
</AIData>
</AbilityBonusOption>
</AbilityBonus>

It would be great to see champions develop other affinities, based around either shards you own (as hypothesized) or the affinities your hero has. Right now, developing them into great casters isn't viable unless they just start with all the affinities you want/need.

I think the whole "Path of the X" is causing people issues, as they don't unlock great bonuses after you choose them, they aren't exclusive of each other, and, as you point out, not all make sense for all characters.

I actually think that having Champions that are better for some stuff and not for other is quite good. If every Champion can end being "Master of the Five Elements", it doesn't sound so cool. I suppose it's a matter of preferences.

I think that the bonuses that you can get after choosing a Path are nice and in some cases really interesting (I'm in love with Tactician and Leadership) but it's true that they are not awesome as the Path traits... which is good or Champions would be totally out of control.

I do not mind champions being restricted in the spells they can cast but I would prefer they have a 'rare' chance to obtain a new school. What I do have an issue with are champions that have path of the mage without relevant spells schools to match.

No Schools, Life Magic, and Earth Magic are good examples, as many talents (such as evocation) have no effect but still clutter the level up options.

Currently, a champion with no spell traits can gain spells:

There is a spell that can be cast on champions to unlock a spell for that champion. They are named differently, but there are these spell-spells for Heal, Fireball, Drain Life, Shockwave. Unlocking these spell-spells (I don't have a better phrase, fuck you) comes from techs.

Check out the in-game hiergammemon on Annointed By Fire for example

I've had champions gain new spell traits, but those always already had atleast one. Not if one with no traits can gain any.

I'm currently taking this personally.

I did not know this, and that is a really good concept for spells that they included.

It's only a handful of spells though, and they're limited in how often they can be cast, so it's still not a great solution to developing a hero with path of the mage, no spells, and the evoker trait (hah).

Should either guarantee a spell school once path of the mage is chosen, or not allow it to be taken if the champion has no spell schools.

There are also some items that allow spellcasting for non-spell traited champions.  Not sure if they interact with Path of the Mage bonus or not.

In addition to those spells that are from the schools, a character that is imbued may also cast any spell that does not belong to any school. Again, these are mostly researched, but some are found.

I will post a full list, based on the XML in 0.75 beta. I will put it in spoiler tags to not spoil any surprise for anyone that does not wish to see it

edit: spoiler tag didn't work. I posted them off-site. Beware of spoilers. These spells may only be for campaign, I don't know. Again, spoilers.

http://pastebin.com/raw.php?i=Kh0XYU8K

The bottom line is this. Path of the mage may not be the best option for someone missing spell traits, but it is far from useless.

I don't consider the Path to be useless because +6 Int means more Exp bonus. It's more about what comes later based on it (like Evoker). 

Hmm Seems that my mind tricked me because I thought that I had Imbued Janusk but seems that I actually didn't. Well, if he can cast those research spells and such, then seems ok.