Upright the Knight of Swords is read as ambition, intellectual drive and the swift, single-minded pursuit of an idea or a goal; reversed, as recklessness, aggression, or a mind moving faster than its own judgment can keep up with.
As a person card, he is conventionally read as brilliant but abrasive, someone whose ideas arrive with force and whose patience for slower processes or other people's objections tends to be thin; readers commonly distinguish him from the King of Swords on the same axis used for the other three suits' knight-versus-king pairs, the Knight as pursuit and unmastered momentum, the King as the same intellectual power already brought under control and exercised with restraint.
Waite's printed meaning for the upright card, skill, bravery and capacity though also possibly extravagance, is somewhat gentler than the aggression many contemporary readers now default to; the harder edge attached to this card in current practice likely reflects the plain force of Smith's galloping picture more than it reflects Waite's own comparatively measured text, another case in the deck where the image has outpaced its author's stated meaning.
The reversed card's warning, recklessness and impatience, is frequently paired in practice with the suit's broader theme, that air's intellectual power is genuinely dangerous when it outruns the judgment meant to steer it, a caution this suit carries more consistently across its court cards than any of the other three.