Cassiel sits next to 5 phonetic neighbors — Castiel, Gabriel, and Raphael are the closest matches by sound. Most share Cassiel's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"my covering is God; God protects"
"recompense of God"
"young wolf"
"causing to forget"
"foreigner, of the Welsh"
"praised, fortunate"
"joy of God"
"God strengthens"
"anointed one"
"holy one (of Dewi/David)"
"famous ruler"
"beloved"
"great, kingly"
"of God"
"dark one"
"fighter, battle"
"rock (via Peter)"
"God has remembered"
"modern invented name with energetic sound"
"peace settlement"
Similar sound: These names share phonetic patterns with Cassiel — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew origins, giving them the same cultural heritage as Cassiel.
Rhythm: Cassiel is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.