Unique/Legendary Boss Damage lvl reqs

I don't think if you already cubed it will get downgraded, It's still referring to the same string in the wz file. You just won't be able to cube it to 30% boss dmg anymore

It seems you're right.

[URL="http://www.southperry.net/showthread.php?t=47169&prefixid=KMST"]
Looking here...[/URL]

Under Old Potential Data, you can find the highest boss damage potential currently in GMS:
"030602/level/1/incDAMr 30"

The 030602 is the reference number for that particular Potential line.

Now, if you dive into the New Potential Data in that same thread and look for 030602, you find:
"030602/info/optionType 10
030602/info/reqLevel 100
030602/info/weight 2
030602/info/string 보스 공격 시 데미지 : +#incDAMr%
030602/level/1/boss 1
030602/level/1/incDAMr 30"

Well, now I have mixed feelings.
On one hand, at least those who have already cubed the hell out of their weapons to get 30% Boss Damage won't be screwed (theoretically), but, on the other hand, it means that I better cube the hell out of my Pyrope sword before Legend hits.
That, of course, is assuming they don't run a script to reassign any current Potentials according to the new rules (which I highly doubt they'll do).