The Link: One-Handed Weapons side quest in Hyrule Warriors: Age of Calamity is a deceptively simple premise wrapped around what can be a challenging mission if you don't know what you're doing.
The goal is to defeat 500 training opponents in 4:00 minutes. This is difficult unless you have a specific plan of attack. I can tell you what won't work: simply button mashing your way through it. Here's how to beat it.
First, attract a large number of opponents into your range before you do anything. You need to focus on filling up your special attack gauge and then use it to wipe out as many enemies as possible.
The best way to do this is combos. Mix in your strong attack after two or three weak ones. Varying strong and weak attacks will also beat enemies more quickly. Use bombs to break their defense as an alternative.
Take care of the Hylian Captains when they appear, because a lot more soldiers appear after you defeat them.
When your special attack meter is full, use it when you're surrounded by enemies. If you move quickly and execute combos well, you can do this a few times. Use combos, special attacks, and remote bombs together to complete this quest. Link's YYYYX combo is especially devastating and launches Link into the air allowing him to quickly travel to the next group of enemies. Efficiency is the name of the game here.
This is one of the game's more difficult missions, so either bump down the difficulty or come back when Link is overpowered and leveled up beyond the suggested level 10 range.
Link earns an Ethereal Stone, Raw Whole Birds, Hot-Footed Frogs, and a random weapon for completion.