Horwath
Legend
this is a problem in class design 1st and then maybe the item design.See, this is the kind of thing I'm not particularly happy about. If this works like this, then every single rogue will have a weapon that does this because- well - it's just too good to not have. Double your attacks per round at the cost of a single minor magic item? Of course a rogue will take this.
To me, that's the definition of unbalanced. If a given option is so good that it becomes the default. That a character would be foolish not to have this.
This is something I'm likely going to have to think about long and hard.
Once per turn is bad mechanic, it begs to find any exploit possible. for any class or any feature.
either rogue needs:
1. have sneak attack on every attack. 3.5e style, or
2. have sneak attack work only once on YOUR turn, not out of turn.
off-topic:
why does sneak attack only works with Ranged and Finesse weapons?
Do we really need one of the worst legacies of 4E for rogue?