I have always wondered why some people pluralize 'power' in certain situations. I've consulted several dictionaries:

Longman:

Most senses uncountable except:

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sense 5ability [uncountable and countable] a natural or special ability to do something: After the accident she lost the power of speech (=ability to speak).
powers of observation/concentration/persuasion a writer's powers of observation

your mental powers
a stone with magical powers
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Oxford learners'

the plural use:

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5 powers [plural] all the abilities of a person's body or mind
E.g. At 26, he is at the height of his powers and ranked fourth in the world.
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It is still unclear to me why power can be pluralized and when it can be/should be.

Please help clarify this :)
Many Thanks