This upgrade would give you the ability to make a JuJu bait item. The bait would attract more JuJus to try to steal from you (and they would go for the bait if they were successful). The more baits you carry (up to a max amount), the more chance of JuJu appearance.
The bait itself would look like a gem trophy, and therefore be composed of one of each gem attached to a board using barnacle talc. So they wouldn't be cheap to make, but if people wanted to pursue their JuJu badges more rapidly, they could use bait. :)