Answer:
Litotes
Explanation:
Litotes as a literary technique is an understatement and it happens when an affirmative is expressed by the negative or the contrary. Examples include, "not a bad player" or "not necessarily".
In the poem Beowulf, at one point, the narrator implies that Beowulf is so strong that his mighty strength breaks the sword blades in half, so perhaps this particular sword actually saves him for once, as it wasn't useless.
