Result of search for "5251":
3676 kec kace apparently a contraction for 3678, but probably by erroneous transcription for 5251:--sworn.
5251 nec nace from 5264; a flag; also a sail; by implication, a flagstaff; generally a signal; figuratively, a token:--banner, pole, sail, (en-)sign, standard.
5264 nacac naw-sas' a primitive root; to gleam from afar, i.e. to be conspicuous as a signal; or rather perhaps a denominative from 5251 (and identical with 5263, through the idea of a flag as fluttering in the wind); to raise a beacon:--lift up as an ensign.