The Items I have used in the proc version for the fauzt and the vizjun video are the same. just check out the fauzt video.
advent of hatred is also a solid weapon, especially for bosses besides the JahXis. For farming there is nothing better than hwanins.
Royal Circlet is a very solid option, but not a must. Reapers is also qute good in the proc version of this build. Also Idol of Rygnar is a viable option.
about the mechanic behind widow maker: it shoots bolts in 4 directions. After that animation is done, the Bolts change their direction to a target once (i think it might be the closest target). if the target moves, the bolts can miss. If there is only one target and it is stationary, for example hitting your minions, all of the bolts will be directing this target.