Two questions: Bloodslayer and Diablo drops

[Gadjan]

I just found something in JR guide. It's about Chamber of Bone but I assume same is applied for Leoric's chests (or am I wrong?).

The chests found in the small rooms on the mini level will create items as if they came from a unique monster, that
is, they will always be magical, have a higher probability of being unique and will use the +4 bonus to the ilvl for
determination of the prefix and/or the suffix.

I suppose "higher probability" is 16%... But does it also means that Bloodslayer can't be dropped from those chests? (2xdlvl)=6 and +4... hello Stonecleaver if I understood JRG correctly.