Everyone seems to pronounce "Lucius" (the name of Sophitia's and Cassandra's younger brother) and "Eurydice" (as in the "Shrine of Eurydice" or the names of characters who appear in SoulCalibur II's Weapon Master mode and SouCalibur III's Chronicles of the Sword) the way they are pronounced in English: "ˈluːʃəs" and "jʊˈɹɪdɪsi" respectively. That's the case even in Cassandra's Soul Chronicle in SoulCalibur VI:
Sophitia's Character Profile in SoulCalibur III
Eurydice's Name Spelled in SoulCalibur VI
However, "Eurydice" comes from Greek and "Lucius" comes from Latin. "Lucius" was a popular given name in ancient Rome and "Eurydice" was equally popular among the Greeks, at least during the Hellenistic period. The way those names are pronounced in their original languages are: "ˈluː.ki.us" and "eu̯.ry.dí.kɛː" My reason for bringing all of this up in the first place is that the katakana spellings in Japanese seem to match their original pronunciation better: "ルキス" and "エウリュディケ."
These katakana spellings have stayed remarkably consistent throughout the series, as did the spellings of names of almost every single Alexandra family member. Almost, because Nike's name was spelled in three different ways.
1. "ニーケ" in Soul Edge the game (can be seen above) and the first SoulCalibur:
2. "ニーカ" in Soul Edge Official Fan Book ~ Chronicle ~:
3. "ニケ" from SoulCalibur II onwards: