While that notion seems impossible or even a bit too convenient, it actually makes perfect sense given the landscape of the Ultimate Universe. Within this corner of Marvel’s multiverse, Weapon X is a much more developed entity than it was in 616 which allowed it to remain a main villainous entity for the X-Men throughout their Ultimate run. Given all the time and effort Marvel Comics put into making Weapon X a major threat in the Ultimate Universe, it only makes sense that the evil organization would improve overtime–resulting in the absolutely terrifying killing machine that is Deathstrike.
While Storm was defeated Deathstrike with a lightning bolt, Yuriko survives and is seen again as a prisoner of S.H.I.E.L.D. before successfully escaping, never to be seen again. Deathstrike disappeared from Marvel canon along with the decimation of the entire Ultimate Universe, which is perhaps the best thing that could have happened for the X-Men. While fighting Wolverine, Deathstrike took zero damage and used the weakness of Wolverine’s healing factor, pain, against him. Deathstrike’s claws were also way deadlier than Wolverine’s as they had the ability to extend and wrap around Yuriko’s victims while also being razor-sharp. All-in-all, Deathstrike proved to be too much for Wolverine to handle, and while her claws were the main factor in her victory over him, it was her impossibly fast healing factor that really put her over the edge as it worked twice as fast as Wolverine’s iconic ability.