Where the soul urge number strips a name to its vowels to get at private motivation, the personality number does the opposite: it isolates the consonants, the letters that give a name its outward shape and its bite when spoken aloud.
For the digit 1, that outward reading tends to track its inward and destiny-based cousins fairly closely — independence and self-direction show up again — but the framing shifts from "what this person wants" or "where this person is headed" to "how this person reads to someone who's just met them."
A personality number 1, in this telling, comes across as someone who takes up space comfortably — decisive in conversation, quick to offer an opinion — regardless of whether that quality matches their private soul urge or their overall destiny number.