Risky is a different concept from Safe. Safe is related to Closet. you are likely to find Suit in/at/on Closet. Suite is etymologically related to Suit. 
Grade is a synonym of Class. 
Risky <--DistinctFrom--> Safe <--RelatedTo--> Closet <--AtLocation-- Suit <--EtymologicallyRelatedTo-- Suite 
Grade <--Synonym--> Class 