So if I put the enchantment for filling soul gems on a sword, I can have less hits for more longer "if target dies within" x amount of seconds or more hits but a less x amount of seconds to kill them in. I don't understand the difference, when I hit an enemy whether it be 4 or 1 second it always fills? Is there a disadvantage to one or the other or a glitch or have I just totally misunderstood haha

Thanks

When you hit them it casts the soul trap spell on them, which only lasts about as long as it says on the enchantment. Meaning you have to kill them before x seconds. If you plan on killing them with that weapon itself, then you might as well only make it 1 or 2 seconds. (i always do 2 just to be safe)

Put it on a dagger with 1-2 second duration and use it to finish off enemies. Thats what I do.

Indeed, as others...I always enchant a Soul Trap weapon for 1 second. It makes no sense to go any further. If they don't die from the first hit, you have to hit them again, anyway.

I always do 1 second for swords and 2 seconds for bows.