
This is a fairly unique signature Weakness, annoying but persistent. Looking at the two elements, the effect and the discard condition, we get:
The effect: fairly simple -- if you succeed, return the token and draw another. This has the unfortunate result that you slow down the game a bit drawing tokens and then redoing the test, keeping track of possible stacking token effects. On Hard/Expert, this can give you lots of extra chances to trigger bad token effects, but it's more manageable in Easy/Standard where the annoyance of going back to the token bag repeatedly is maybe greater than the actual mechanical effect.
The discard condition: Fail a test. However, that just puts it back in your deck. Given Seeker card draw, it's not unlikely you will see this over and over.
All in all, this is an average signature weakness, maybe above average on harder difficulties. it can end scenarios by piling on Doom, Horror, or Damage in worst case scenarios.