The next Fortnite Deadpool katana should be located in the agents tab by Brutus or TNTina in their armoury.
You can also find Fortnite Deadpool katanas in-game at the lair inside the newly added skull POI.
You need to head through a vent in that location to find an area housing a pair of Deadpool’s katanas that are on display.
In case you’re wondering, here is the full list of Deadpool challenges for week 4…
• Find Deadpool’s katanas – 2
• Deal damage to opponent structures – 10,000