I'm really lost on soul gems. If I'm enchanting a item to give it fire damage and I use a grand soul gem opposed to a petty soul gem (not refilling, i'm attaching an enchantment to the weapon), what's the difference? Will it do more fire damage since I enchanted it with a better soul gem?

I understand soul gems can refill weapons and the bigger the soul gem, the more it refills but I'm talking about actually enchanting a weapon for the first time. What effect does the tier of soul gem have on the weapon.

Also, I was looking at bows to buy from a vender and 1 sold a bow with no enchants that had 24 base damage. Another bow he was selling only had 14 base damage but had an enchant saying 10 damage of frost to health and stamina. Does that mean this bow has 25 damage and it fatigues them a little also?

Thanks!

The soul gem affects how strong the enchantment is, with weapons you can choose how much elemental damage and how many charges (more elemental damage = less charge), with a better gem you have a larger option for elemental damage and charge. Well thats the case with 1H weapons anyway (all I use+spells)

The higher base damage bow is probably the best one to go for, as the other will run out of charge. But the other one does stamina damage, your call.