Limit is related to Credit. Credit is related to Merit. Merchant is etymologically related to Merit. 
Plastic can Melt. Melt is a type of Weaken. 
Limit <--RelatedTo--> Credit <--RelatedTo--> Merit <--EtymologicallyRelatedTo-- Merchant 
Plastic --CapableOf--> Melt --IsA--> Weaken 