You can replace that shaft with any on the market. Since that shaft came with the Ping ISI Irons and had a firm flex, since the W44 were regular, you should get a stiff shaft put in for a replacement.
The W54 graphite Ping shafts are a specific type of golf club shafts manufactured by Ping. The "W" likely refers to the weight of the shaft, with W54 indicating a 54-gram shaft. Graphite shafts are known for being lightweight and providing more flexibility, which can help golfers generate more clubhead speed. These shafts are designed to provide a balance of distance, accuracy, and feel for golfers looking for a lightweight option in their clubs.
The W54 nuclear warhead used in the Davy Crocket, AIM-26 Falcon air-to-air missile and the SADM atomic demolition munition was a variable yield, linear implosion warhead most likely with an unreflected bare ovoid pit. It boasted a variable yield of 0.01 kilotons (10 tons of TNT) or a variable yield variant of between 0.02 kilotons-1 kiloton. (20 tons of TNT - 1000 tons of TNT) The cost to develop this weapon is not that easy to find, but many estimates and research have shown a price of anywhere from 14 - 40 million per weapon, not including the delivery system.
The smallest nuclear bomb ever developed is the W54, which was used in the Davy Crockett nuclear weapon system by the United States. It had a yield of 10 to 20 tons of TNT equivalent.