Ethnic bioweapons, i.e. weapons designed to kill a particular ethnic group, sound like pure evil. For most of history, they've been used solely for evil. In one case, though, removing a "weapon" ended up being a humanitarian disaster.
The Terai region in Nepal is covered with wet, dense forest, and inhabited by a group 0f people called the Tharu. There aren't many ways to encapsulate the Tharu. Different subgroups have different cultures and dialects, but they all share one important trait. They are resistant to one of the world's most famous killers: malaria. Cases of residual malaria are about seven times lower in the Tharu as they are in other populations. Up until the 1950s, the Tharu lived in jungles that other people could not safely enter without daily medication.
Then the World Health Organization started up a malaria eradication program world-wide. They worked to eliminate malarial environments, and malaria carriers like mosquitoes. They did so well in Nepal that non-Tharu people streamed into the Terai region. Some merely settled there, but others inducted the Tharu into forced and often lifelong labor. Though the practice of "bonded labor" was outlawed decades later, Tharu still remain an underclass in the region. Given the outcome, some Tharus consider the elimination of malaria from the area not a humanitarian effort but a clearing of the path to colonization. Lately, anthropologists have been looking at the different ways that indigenous groups maintain their environment. Not all maintained land looks like farmland. Given the Tharu tolerance for malaria, their ancestors may have maintained a habitat for a bioweapon in order to hold their land. In this case, it's important to note that the weapon was a shield, not a sword. But it does give us another way to look at development. For some people, it's a blessing. For others, it's stripping them of their defenses.