P/C>A beam whip.

On a hunch, I would say it's around 2.5-3.5b (considering the Unleashed Store is gone), but it's very difficult to gauge prices in this current market.
I think the best option would be to set up a permit and take offers on it for a few weeks.
I don't know how many Unleashed scrolls you have left, but if you don't have anything else to use them on, or if you think it's worth spending event clean slates in case the scroll doesn't work, then I would finish it off. Scrolling the last slot is partly for visual appeal (so it feels "completed" and has a better chance of selling), it really shouldn't affect the price too much.

Wow. I didn't think I'd ever make an item worth over 2b.
I've 18 scrolls, at least 10 will be going towards my phantom's cane, some may go towards the start of a beryl heart(finishing with RED scrolls). So I've around 5 to put towards that slot. Thanks for the answer!