The Lambda Driver is a piece of Black Technology capable of turning willpower into physical force. It is equipped onto several select Arm Slaves in the series, including the ARX-7 Arbalest, Sousuke Sagara's Arm Slave, and various models of Venom, Gauron's Arm Slave.
Officially called the "false axis repulsive field generator system", the lambda driver is a pure Black Technology device capable of exerting mechanical force against space with no observable physical interaction. "False axis" refers to the lack of physical interaction, or lack of momentum in the application of torque. This is in direct violation of Newtonian physics, particularly Newton's Third Law. However, recent research showed that this law does not apply to a room that is curved by gravity, therefore using the curving of space as leverage is possible.
A select few Arm Slaves possess the device called the Lambda Driver which can manifest emotional thought patterns into raw and devastating physical power. In Full Metal Panic! (first anime series), Sousuke Sagara's ARX-7 "Arbalest" has a Lambda Driver (but due to Sagara's lack of experience, it only served to aid him most minimally and improved as time progressed). Every instances where Sousuke has engaged an enemy with the superior skill using the Lambda Driver (especially Gauron on three counts) Arbalest's Lambda Driver was still capable of defeating them.
Sousuke often (at least initially) found himself at a disadvantage while fighting other Arms Slaves equipped with a Lambda Driver because unlike Amalgam, Mithril had supplied Sousuke with no training and no drugs to help in mastering the Lambda Driver. For example, the Lambda Driver equipped on the Behemoth was needed just to keep that AS intact, let alone to have it function optimally. Its pilot, Takuma Kugayama, had no problems using the Lambda Driver with the medication("TI-971") and training he had received.