> Split scimitar winglets are named for the curved Middle Eastern sword, extending above and below the wing, and ending in sharp points. They have been found to produce up to 5.5% fuel savings per aircraft, an improvement on the 3.3% savings provided by blended winglets.
That's the reason, the rest of the article is fluff meant to keep people on the page and seeing ads because it obscures the answer they came to see.
Delta uses "Split scimitar winglets" ... "to produce up to 5.5% fuel savings per aircraft, an improvement on the 3.3% savings provided by blended winglets."