Learn Polish: On nie czuje niczego, wszakże nie ma sumienia. - He does not feel anything; after all, he has no conscience.

Both words can translate to "after all" or "as you know," but wszakże belongs to a much higher, more literary register. While you would use przecież in everyday conversation, wszakże adds a dramatic, almost poetic weight to the sentence, emphasizing that his lack of conscience is an undeniable fact.

Does the suffix -że in wszakże change its meaning compared to just wszak?

No, the core meaning remains exactly the same. The -że suffix is an emphatic particle that simply adds a bit more rhythmic weight to the word. You can use wszak and wszakże interchangeably, though both sound quite formal.

Why does the sentence use niczego instead of just saying nie czuje nic?

This is the "Genitive of Negation" in action. The verb czuć normally takes an accusative object, but when negated, the object must switch to the genitive case. The genitive form of nic is niczego. In everyday colloquial Polish, people often just say nie czuje nic, treating the short pronoun as an exception, but niczego is the strictly correct grammatical form and perfectly matches the formal, elevated tone set by wszakże.

I have seen wszakże translated as "however" before. Is that what it means here?