Obviously you can use the weapon you find or purchase, but enchanting your own will typically yield better results. If you would rather use the Soul Trap weapon enchant, then first you must find a weapon with the Soul Trap enchant on it in order to disenchant.
You can not have more than one active Soul Trap at a time. Once Soul Trap is placed onto an enemy, it lasts for 60 seconds. If you’re going to use the Soul Trap spell method, then you just need to purchase the spell book from a magic vendor. long and short range for example) with the Soul Trap enchant is the best way to go, that way you don’t have to keep switching to the Soul Trap spell when you need it. Personally, I think having a weapon (or several for that matter.
You can either cast the spell yourself, or enchant a weapon with the Soul Trap enchant. In order to fill a soul gem, you need to use a form of the Soul Trap spell. In The Elder Scrolls V: Skyrim for the PC, PS3, and Xbox 360, soul gems are used to trap souls, which can then be used to enchant or recharge magical equipment.
