Freezing an enemy leads in fact to giving him a kind of armor. But I think this happens on purpose. You have to hack through the ice before you hack hit the enemy...
The major benefit of freezing is to take the respective enemy "out of the game" for a few turns which gives you the ability to fight against other enemies. Freezing an enemy is imo not an attacking or damage inducing spell, but a secondary spell.
Hitting a frozen enemy with fire can end his frozen status (if burning suceeds) IIRC. The other way works as well. Freezing or chilling a burning or warmed enemy ends his current status if the spell suceeds).
Lighthouse combat is difficult??? Not in my game...
The lighthouse combat was much easier than the one against Braccus himself or the fight against his court of sceletons which is imo the most difficult combat encounter in the game.
