Dealing with high protection

Besides Air Magic, Nature gives you some nice spells to start with. Sleep (starting spell for Man) is now better than Paralyze because the target keeps the high fatigue for the battle. With 110 fat your opponent loses 11 def and most hits negates half of the armour ! (I've killed a knight with 26 prot and 22 def in one round with some modest archers Last night, thanks to Sleep).
Tangle Vine is easy to reseach and can negate high def I believe.
Sleep Cloud needs some more reseach, but the area is larger.
Cheers