Answer:
Oxymoron.
Step-by-step explanation:
A figurative language also known as figures of speech can be defined as a deliberate and specific construction or use of language by authors, writers or speakers to create a special effect in their speech or write-up.
The main purpose of a figurative language is to convey more information and enable the readers or listeners have a deeper understanding of the piece. Some examples of figurative language used in a literary work are simile, paradox, metaphor, apostrophe, hyperbole, personification, oxymoron, etc.
An oxymoron can be defined as a figurative language that comprises of words or phrases that are contradictory. Therefore, an oxymoron involves the intentional use of words or phrases that have opposite meanings.
The quote "A powerful weakness came over him as he stepped out of the shower." is an example of an oxymoron. This quote qualifies as an oxymoron because the words "powerful" and "weakness" are contradictory i.e have opposite meanings.