Opinium cores which are in mystic chest

[Dustin20056]

So I just just used a mystic chest key and got 8 opinium cores (perfected) but the thing is there isent actually a use for them anymore  they used to be for kikoku,compound bow but the recipe being changedmakes the cores have no purpose so I'm wondering if it's an oversight on puting the highest value chest with a chance to get a unuseable item or if iv overlooked something