What is the word that means can be or harmful to depending on point of view?

The word which means "can be helpful or harmful depending on the point of view" is beaver. Beaver can both have a good and a bad effect to the ecosystem. In a good point of view, beaver serves as natural filters segregating sediments from flowing to bodies of water. On the other hand, it can also cause flooding.

It improved the ability of the united states to provide military support to the allies.