Hi, according to Minecolonies developpers, Mekanism weapons would be missing the minecraft "weapon class" that would allow the guards use the Mekanism swords.
They already use some tools like axes, pickaxes and shovels, but not the hoe.

ldtteam/minecolonies#2270

https://github.com/aidancbrady/Mekanism/blob/3e469fb40a2a086527cf14dbe9ba709f708a9bca/src/main/java/mekanism/tools/item/ItemMekanismSword.java#L15

The Swords extend vanilla's ItemSword, so they're talking bulldust