The +16 ceiling on weapon and sidearm upgrades in Mortal Shell 2 is not permanent. It comes off once you retrieve the Endless Core from The Hidden Nave beacon dungeon near the end of the campaign and slot it into the Tarforge back in Marrow Keep. After that, the Enhance Weapons and Enhance Sidearms menus keep counting upward, all the way to +99.
Quick answer: Cleanse The Hidden Nave beacon inside The Unfound Path, pick up the torch to cross the fog, loot the Endless Core from the flooded chamber, sacrifice all your Gloom at the sealed door, cleanse the Corruption Core, then install the Endless Core at the Tarforge anvil to remove the +16 cap.
Where the Endless Core sits in the campaign
The Endless Core is a late-game pickup. It only becomes reachable once you enter The Unfound Path, the final major dungeon, and clear out the corrupted tendrils blocking your way. Doing that reveals The Hidden Nave beacon in the middle of the zone, positioned right before the last boss encounter. Everything past this point carries heavy ending spoilers, so treat the area as endgame content.
Approach the darkened tree structure at The Hidden Nave, revitalize the beacon, and choose Cleanse Beacon to drop into its dungeon. The Endless Core is the reward waiting inside.
Solving The Hidden Nave cleanse dungeon
The dungeon is a dark, foggy cave. The mist turns you around if you try to push through it blind, so the first job is finding light.
Tip: The gate takes every point of Gloom you are carrying. Trigger the doorway before you crack open the Gloom-filled chests scattered nearby, so you can bank those resources afterward instead of feeding them straight into the sacrifice.
Installing the Endless Core at the Tarforge
The Endless Core is the one Tarforge upgrade that is not handed to Franz. It goes in through the forge menu itself.
You will know it worked when the Enhance Weapons and Enhance Sidearms functions stop stopping at +16. Levels above that become selectable, and the game shows the higher-tier smithing stones as the required material.
What upgrading past +16 costs
Every weapon and sidearm level costs Coins plus a smithing stone, and the stone changes as you climb. Each stone locks to a fixed band of levels, so a stone you cannot yet use tells you how far the weapon still has to go. The Endless Core is what makes the top bands accessible.
| Smithing stone | Upgrade levels | Notes |
|---|---|---|
| Ventrium | +1 to +5 | Common, early game |
| Laterite | +6 to +10 | Common, mid-game |
| Dorsalite | +11 to +15 | Uncommon, late game |
| Theoracium | +16 to +20 | Rare, endgame |
| Ossinite | +21 to +25 | Endless Core required |
The upgrade path keeps going beyond +25 up to a maximum of +99 once the cap is broken, but the higher levels demand large Coin and stone totals. Reaching the very top of the ladder normally means grinding those materials rather than hitting a single wall. If you ever over-invest, the Smelt Equipment function reverts an armament to +0 and refunds the smithing stones you spent.
If the cap is still stuck at +16
A few specific things stop this from working:
- You cleansed the beacon and cleared the dungeon but never picked the Install Endless Core option in the Tarforge menu. The core has to be installed manually; simply owning it does nothing.
- You tried to cross the fog without the torch and got turned around. Return to the first campfire, confirm the torch has spawned, and carry it in.
- You refused the Gloom sacrifice at the sealed door. The gate to the Corruption Core will not open until you give up all your Gloom.
- The base upgrade function is still off. Enhance Weapons needs the Muradean Actuator and Enhance Sidearms needs the Obsidian Lathe before the Endless Core’s raised cap has anything to apply to.
With the Endless Core installed and enough Coins and high-tier stones on hand, your main weapons like the Axatana and sidearms like the Caged Hystrix can be pushed far past their old limit, giving you a large damage jump for the closing fights and any New Game Plus run that follows.
