The merchant returns in Capcom's Resident Evil 4 remake with his old swagger, and a new penchant for side quests. One of his requests is to find and kill "A Merciless Knight" somewhere in the halls of Ramon Salazar's castle. This guide will arm you with the info you need to find and slay the fiend.
Where to find A Merciless Knight
Chapter 9 of Capcom's Resident Evil 4 remake leaves off with Ashley back in the clutches of Ramon Salazar's minions and Leon determined to find her. You begin in the cage where Leon was trapped before you took command of Ashley and guided her through the Library and Mausoleum. Once you pick up the merchant's "A Merciless Knight" blue note request, the merciless knight in question will take up residence in the Mausoleum. Killing it will earn you eight spinels, your biggest payout so far, but be ready--the knight has backup, and none of them go down easily.
Exit the cage and pick up any of the items Ashley threw down to you. (The more treasure you collected as Ashley, the more Leon will have to pick up.) Now head to the */*/AREA where you'll find the "A Merciless Knight" blue note pinned to a column. Adding the request to your collection of files causes the knight to appear in the Mausoleum. To find him, you'll need to return to the library where you played as Ashley.
On your way through the Library and down to the Mausoleum, you'll come across the same Las Plagas-infected suits of armor that made poor Ashley swear off suits of iron forever. (Just don't tell her about the game's unlockable outfits.) You can destroy them as Leon, but they're easy to dodge, and you'll need all the firepower at your disposal to deal with the merciless knight.
Take the elevator down to the Mausoleum. The merciless knight is hard to miss: It's a golden suit of armor at the far end of the crypt, flanked by two normal suits of armor. They'll come to life when you're approximately halfway from their location. Before that, loot the vases to either side of the stairs leading into the Mausoleum. Each should contain an assortment of pesetas and, more importantly, ammo and gun powder.
The merciless knight has sweeping attacks and a lunge that give it greater reach than regular suits of armor. There's no right or wrong way to defeat these walking rust buckets, but there is an efficient way. Use your strongest firearms to break their helmets, causing the Las Plagas to emerge. Shotguns and grenades inflict damage in a wider radius, making them more useful than handguns, rifles, and the TMP, though any weapon will do the trick. When all three stalks are exposed, toss a single Flash Grenade to destroy them.
After reducing "A Merciless Knight" and its minions to scrap metal, collect the treasure they drop and return to the merchant to receive your eight spinels. With that finished, return to the Shacknews Resident Evil 4 strategy guide, where you'll find more walkthroughs for all the Blue Medallions in the game.