“ In one region of a forest, all of the trees are identical, down to the leaves and the twigs. If the PCs carve something into one of the trees, it could mystically propigate until it covered all of the trees, or could vanish since it was not carved into the one true tree.”
“ Silk Armor? The Mongols wore silk undergarments under layers of leather armor. Why? Because silk is very strong. If an arrow hit them and made it through their armor, it would usually not have enough energy to puncture the silk. It could still enter their body but, because the silk would not break, the arrow's barbs could not do their work and the arrow could easily be removed leaving a relatively clean wound considering normal arrow wounds.”
“ A kingdom where, if there are multiple princes (princesses can't rule unless they have no siblings), the princes fight to the death in the arena to decide who gets to rule. A simple way to make sure your brother cannot make a bid for the thrown, and keeps the royal blood in one line.”