Hello. I haven't really explored enchanting but I like to use it a bit. I'm wondering why I can't put certain enchantments on armour that goes on certain parts of the body. Helmets for instance. All I can put on a helmet is bow and blade damage. What I would like is frost or fire protection. Is it possible to do that if I raise my skill or is it not possible? I've noticed some the Helm of Yngol has frost protection.

Also when I try to put bow or blade damage on something the most I can do is 13%. This is going to sound weird but due to my OCD I have a thing for rounding and would really prefer 10 or 15%. How much do I have to raise my skill to get that 2%? Or is there a way to somehow adjust the ehchantment strength so I could just make it 10%?

Thanks very much.

Every type of enchantment is limited to certain types of items. The limits are designed in such a way that you can only have 4 enchantments of the same type. It's an arbitrary decision made by the game desingers, probably intended to limit the power of the skill. Which is funny because Enchanting actually is the most powerful and versatile skill in the game (with the possible exception of Alchemy). They could've simply made all the enchantments only half as strong but available for all items and it would've been perfectly fine.

You can't really manually set the magnitude on apparel enchantments. With 100 Enchanting skill, 5 ranks in the Enchanter perk, the Insightful Enchanter perk, and a grand soul the Fortify [weapon skill] enchantments will have a magnitude of +40%.

You will probably find this page useful: http://www.uesp.net/wiki/Skyrim:Enchanting_Effects

More specifically, you might be interested in the formula that determines the amgnitude of enchantments: http://www.uesp.net/wiki/Skyrim:Enchanting_Effects#Effect_Charges_and_Strength

Not all items can use the same enchantments. For example, Helmets cannot use Resist Fire.
http://www.uesp.net/wiki/Skyrim:Enchanting_Effects outlines which pieces can use which enchantments.
Your skill has no effect on that.

To get higher than 13% you need to raise your Enchanting skill, or drink a potion that temporarily boosts it.
Some perks will also increase the % for some things.

edit: Ninjad.... too slow