Why doesn't Cervantes other weapon options seldom replace Nirvana, only replacing Acheron?

The only instances I've seen that BOTH Acheron and Nirvana gets replaced is with the flags in soulcalibur 6, and the player2 weapon from Broken destiny (and presumably soul calibur 4)

This is very weird considering Cassandra and Sophitia replace both the sword and the shield.

Does this imply Namco never cared about Cervantes as much as they did to other characters and were willing to cut corners regarding him?

(Using past tense because they do not care about the entire soulcalibur franchise now, from what I understand

Also I know this may be sort of an overanalysis)

Also, what methods do you use to make that pistol sword unique as possible on custom characters, despite the limitation of always having the same model?

The only instances I've seen that BOTH Acheron and Nirvana gets replaced is with the flags in soulcalibur 6, and the player2 weapon from Broken destiny (and presumably soul calibur 4)

This is very weird considering Cassandra and Sophitia replace both the sword and the shield.

Does this imply Namco never cared about Cervantes as much as they did to other characters and were willing to cut corners regarding him?

(Using past tense because they do not care about the entire soulcalibur franchise now, from what I understand

Also I know this may be sort of an overanalysis)

Also, what methods do you use to make that pistol sword unique as possible on custom characters, despite the limitation of always having the same model?