Self-loathing, admiration, integrity. What Marlow suggests, more than the blaze of glory Kurtz is going out in, is the lack of own reason and deathbed soliloquy he himself couldn’t fulfil. “I found with humiliation I would have nothing to say.” Marlow describes with such admiration, the victory of morals Kurtz has achieved. Although his tribulation may have defeated him in body, “since I had peeped over the edge myself”, the admiration also strongly suggests an inherent resentment in himself. So in talking about himself in comparison to Kurtz, knowing that his number was up, though in death, aspects of life can appear so mundane, the tying up of loose ends with a final gained sense of self, Kurtz monologue was aloof with wonderous marvel compared to the lesser man’s (Marlow himself).
The motif of the candle in death alludes to, I think the light of civilisation Kurtz was intended to bring and share in Africa. Though Kurtz could not see the light in front of him, Marlow reveres him saying he had captured a glimpse, suggesting that he had perhaps transcended even the status of man in his own sense of actualisation. This literary criticism parallels the emptiness felt in the absence/death of what we feel is “great” or “remarkable”.
Beyond Kurtz’ death, the lie Marlow gives to Kurtz’ betrothed, further alludes to the lie we must tell ourselves, in western society, that the innocents must never know the price of liberty that has been paid for with the truth.
That's what I think anyway, seems to hold some legitimacy in this claim.