An "honourable death" is not really about the
death, but the life of the
recently deceased. Accepting for the moment the argument that there is no
afterlife, there still is meaning in
sacrifice when you
see yourself as part of something greater. In a sense, the death represents ultimate
humility, where a person realizes that while his or her life has value, others are worth more still. In this case, the act is in not about death, but life.
When a person dies "honorably", their death is an act of personal sacrifice on behalf of another. Perhaps in battle fighting for a cause, or during dangerous rescue, the person giving his or her life did so for something greater than themselves. Humans are a social species. We are not happy, and really do not exist outside of communities. Often we as people derive our identity at least partly as a member of a community. We are also members of a species that builds and grows on the work of others. In essence the human community is engaged in continuous growth and social evolution.
The Jesuit priest and evolutionary biologist Teilhard de Chardin wrote of this in his books, which include The Phenomenon of Man and Building the Earth. Chardin saw in the evolution of humanity evidence of a goal, which he saw as evolution toward the Godhead. In his writings he employed many metaphors employing the biological systems he studied. He saw the interconnections of communications and data analysis as forming a noosphere, a loose general consciousness which he compared to the human brain. Chardin saw a purpose in evolution and the struggles between ideas and civilizations. We were evolving toward the Omega Point where we would have developed the tools and wisdom to deal with our social ills, and would build a utopian society. As a Christian, de Chardin saw this as moving toward God, a God who wanted his children to grow up.
Even if you discard de Chardin's theology and choose atheism, there is evidence of human social evolution. We have come a long way since biblical days, where slavery was commonplace and openly accepted, where women were chattel valued primarily for their wombs. All of human history can be seen as an act of learning, not so much as individuals but as a species. We fail, we screw up, we take two steps backward, but humanity has the potential to grow into something greater than we are. We are not finished products, but are still learning to be human. We will not live to see our promise fulfilled, but we have children, as will their children. Our purpose is not just to live our lives, but to live them in a way that makes things better for our descendents.
A person who meets an "honourable death" is a person who gives their life for this greater goal of a better world. In their death is the seeds of life for their children, or the children of those they love. Selflessness can be perverted when sacrifice is done in the name of hatred, but as long as people are willing to give everything for others, there is hope for the rest of us.