I disagree that this damages lore. I mean look at Battlemage Jaes (before he was renamed for Crown of Destiny). A mage with a big sword.

Additional examples of "cross-archetype" heroes:

Lyssa- she's pretty scouty/warriorlike for a mage

Andira and Jonas- definitely have some knight qualities as far as healers go

Durik and Nara- These warriors are quite rogue-like.

The list goes on.

You're correct Zaltyre, those heroes are excellent examples of those that make sense for hybrid-classing.

Sadly though there are many heroes for which a hybrid class is much more jarring. I mean, imagine Serena the Berserker!

Sounds kind of adorable, actually..