You can have sword/bow and arrow/egg duels in a stadium. The two players should empty out their inventories and only keep their single weapon of choice (infinite arrows for the bow is allowed, as long as there is one empty slot), then put in the reward for the winner/killer. An example would be for someone to have a diamond sword out, but in their inventory could be five stacked lapis lazuli or a single block of diamond. You can also have bigger quantities of items; it does not really matter, as long as both players are fair and have the agreed-upon reward in their inventories. Then have the two players just fight (no health hacks and no death chest mod). Armor is allowed, but it is recommended that rules be set regarding it. Whoever dies first loses, and everything in their inventory will be dropped. The winner can pick it up.