Plain is related to Boring. Boring is the opposite of Interesting. Interesting is similar to Fascinating. 
Blade is related to Very. Very is related to Space. Space is related to Darkness. Darkness is related to Shade. 
Plain <--RelatedTo--> Boring <--Antonym--> Interesting <--SimilarTo--> Fascinating 
Blade <--RelatedTo--> Very <--RelatedTo--> Space <--RelatedTo--> Darkness <--RelatedTo--> Shade 