Why is the blackout passive on duskblade?

when spotted by a ward, disable traps and reveal wards around you for 8 seconds

This seems like a passive effect you'd primarily want on a either support or a jungler. I mean yes an assassin can use it for ganking, but I think the roles of support and jungler could make better use out of it overall. Your jungler is most likely going to be the one spotted by a ward in the early to mid game, so it makes sense on him, while support/junglers are traditionally most responsible for vision and map awareness. Another point for the support having this effect is bot lane has access to the most wards early on, so something like this on a support item would encourage even more interaction and ward fights.