That should be the default situation, so no action required there.BladeC36 and BladeC37 can be sold in stores
Set it to 0.0 for its "rare" value in initItems.c and add it to the "unique" code in that same file.and BladeC38 can only be found in any Treasure chest on a ship
Then find the Treasure code in PROGRAM\MAXIMUS_functions.c and include a line for it there.