In the skill window, the Enchant Weapon icon should be shown whether you have the view set to available skills or all skills, since level 1 has a requirement of character level 1. Maybe try learning the skill from within
iZakaroN's SaveEditor.
When editing the config.div file, did you just change the listed height and width values, and make sure you didn't add any extra spaces, mix up the two values, or something? I've edited that file a few times to try different resolutions, and the game never popped up the dialog about resetting the configuration.
The majority of my resistance came from equipment bonuses, though I did max Magic Barrier as well. I maxed Spell Shield and Aura of Guarding from purchased spell books, though that would be harder to do in the wastelands, with fewer merchants. Spell Shield is particularly helpful to protect against poison.
If you are comfortable hex editing, you can change your resistances directly (see
Some more hex offsets... and
Teleporting Anywhere, via hex editor). For smaller bonuses, you can use the save editor to unlearn Magic Barrier, load, learn it again, save, unlearn (as required), re-load... (see
help with negative resistances).
Also, you could just use
DAD's item editor to add a resistance bonus to armour or jewelry (I have not used it in quite awhile, but I'm pretty sure it can do that).
