Metallurgy & Divine Incarnations

In Hindu mythology, Rama & Krishna are considered Divine Incarnations. But in their sojourn here, they had perforce do many ambiguous things. Like Rama shooting Vaali from behind a tree & subjecting Seetha to repeated tests. Similarly Krishna, during the battle, suggesting the killing of Karna & Duryodhana. 

One way of looking at these things is to study Metallurgy, where one finds pure forms of rare metals very rarely useful. Only when they are alloyed with base metals, do they become useful for daily activities.

Similarly noble qualities like truthfulness, honouring promises etc., may have to be alloyed with a little deviousness & expediency in order to survive in this world, even by Divine Incarnations!