The ‘Chink in their Armour’ skill is not specified as only effective for ranged weapons
Chink in their Armour
+10% Rending when at, or over, 10 stacks of Focus
By the way, the word ‘Chink’ has a derogatory meaning in certain contexts. It is recommended to replace the name of the skill with another one, otherwise it may cause misunderstandings
It is entirely possible to use words like ‘credit’ to replace this meaning