To farm Weathered Crisis Fragments efficiently in Path of Exile 2, focus on these optimized strategies:

Reach and Run Tier 15 Atlas Waystones
Weathered Crisis Fragments drop primarily from the Stone Citadel boss Doryani, which appears at Tier 15 maps. Progress your Atlas to unlock and consistently run these high-tier Waystones to access the relevant Citadels.

Maximize Waystone Drop Chance

The quantity of Crisis Fragments per Citadel clear is strongly influenced by your Waystone Drop Chance stat.

Only suffix modifiers on Waystones increase this chance, so craft or buy Waystones with many suffixes.

Use Vaal Orbs to corrupt Tier 15 Waystones, which can turn all modifiers into suffixes (up to six). Six-suffix Waystones significantly boost fragment drops, often yielding 2-3 fragments per boss kill, sometimes 4 with very high drop chance.

Beware that six-suffix corruptions make the maps much harder due to negative modifiers, so ensure your build can handle the increased challenge.

Invest in Atlas Passive Tree for Waystone Modifiers

Respec your Atlas passive points when farming Weathered Crisis Fragments to pick nodes that increase Waystone Modifier Effect and Waystone Drop Chance Bonus. This amplifies your fragment yield per run.

After farming, revert to your normal Atlas setup for other farming activities.

Use Precursor Tablets and Lost Towers Nearby

Place Precursor Tablets and clear Lost Towers near your Stone Citadel maps to further increase the quantity and drop chance of Waystones, enhancing fragment farming efficiency.

Efficient Atlas Routing and Citadel Chaining

Plan your Atlas progression to reveal and chain multiple Stone Citadel maps in succession to maximize the number of fragments you earn per hour.

Use map modifiers and atlas routing that enhance map density and speed to clear Citadels faster.

Prepare Your Build for the Increased Difficulty

The negative affixes on six-suffix Waystones stack to make Citadel bosses and encounters significantly harder. Build survivability, damage, and crowd control to efficiently clear Citadels without dying (death means map loss and loss of the Waystone).

If your build is not ready for six-suffix corruption, start with fewer suffixes for safer runs but expect fewer fragments per clear.

Optional Group Play

Running Citadels in a team can speed clears and improve survival against tough boss mechanics, increasing fragment farming rates.

Currency Exchange Alternative

If you prefer not to farm, Weathered Crisis Fragments can be bought from Currency Exchange NPCs starting after Act 3, but this is less efficient and more costly for bulk acquisition compared to farming.

In brief, the most efficient Weathered Crisis Fragment farming comes down to running high-tier Stone Citadels on six-suffix corrupted Waystones with optimized Atlas passives and map routing, while preparing your build for the added difficulty to maximize fragment drops per run.

This approach will accelerate your collection for the Burning Monolith keys needed to face endgame content, or provide substantial trade opportunities from selling excess fragments.