Sigel sits next to 4 phonetic neighbors — Sigil, Cecil, and Siegel are the closest matches by sound. Most share Sigel's Germanic cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"sun"
"loving, affectionate (if from Philemon)"
"scholar"
"dark river, dark stream"
"bright one, radiant"
"skilled metalworker"
"field settlement"
"Ford by the windy place; a river crossing in a breezy location"
"Brave as a boar; strong and courageous"
"old, wise ruler"
"glory of the homeland"
"from the alder grove"
"house of God (possible Bethel derivation)"
"associated with Saint Spyridon, miracle worker"
"nobleman, pledge"
Similar sound: These names share phonetic patterns with Sigel — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Anglo-Saxon origins, giving them the same cultural heritage as Sigel.
Rhythm: Sigel is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.