In riverwood if you break into faneral's house and into his chest there is a dwarven bow of binding and it fills a soul gem if you kill the enemy with in 7 seconds

dude, thanks!

(7 seconds...that's insane though... you have to use the bow to kill in that time?)

Also... is that 7 seconds from the time the last arrow hits or the first arrow hits ... can you reset the count?

not sure I just use it on deer and wolves and one hit em

There are several weapons like that. I have an Iron Mace of Binding that does the same (7 seconds). The time appears to run from the point of the most recent strike by that weapon until the target dies.

That was a random find, it won't be there for everyone. With soul trap, you are much better of just enchanting 1 second, it will always trap the soul when killing an enemy with that weapon, and you get more charges.

I enchanted my dwarven warhammer with soul trap of 1 second duration. More than enough. Every time you strike your weapon, it loses charge and the timer resets.

Thanks...that's what I wanted to know. So, it does reset. cool.