What do "unredressed" and "make himself felt" mean?
It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.from THE CASK OF AMONTILLADO by Edgar Allan Poe (1846)

"The thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult I vowed revenge. You, who so well know the nature of my soul, will not suppose, however, that gave utterance to a threat. At length I would be avenged; this was a point definitely, settled --but the very definitiveness with which it was resolved precluded the idea of risk. I must not only punish but punish with impunity. A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.""It must be understood that neither by word nor deed had I given Fortunato cause to doubt my good will. I continued, as was my in to smile in his face, and he did not perceive that my to smile now was at the thought of his immolation."

Question

What do "unredressed" and "make himself felt" mean?
It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.from THE CASK OF AMONTILLADO by Edgar Allan Poe (1846)

"The thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult I vowed revenge. You, who so well know the nature of my soul, will not suppose, however, that gave utterance to a threat. At length I would be avenged; this was a point definitely, settled --but the very definitiveness with which it was resolved precluded the idea of risk. I must not only punish but punish with impunity. A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.""It must be understood that neither by word nor deed had I given Fortunato cause to doubt my good will. I continued, as was my in to smile in his face, and he did not perceive that my to smile now was at the thought of his immolation."

Answer

To "redress" something is to put right a wrong situation e.g. by financial compensation, apology, or some kind of action.  So if a situation is "unredressed", it means that an injustice has been done but not been corrected.  I have never seen the word before so I would be careful about using it.

"to make yourself (or your presence) felt" is to do something which lets others know that you are present and your interests or opinions need to be heard or otherwise accounted for.  I don't know why this expression is used in this context.  It is certainly a funny excerpt and may be from an old book.  "Make himself felt" may have had a different meaning in the past.  Is there any more context?

Answer

Unredressed is like unavenged.  Their wrong has not been addressed (corrected).

Revenge is unserved when the victim doesn't do any damage to his attacker.

Or it could be that unless the evil doer knows it is the avenger doing him some harm the wrong will not have been redressed.