The Highlander's massive HildCo jump jets were designed to lift the BattleMech over inconveniently placed buildings, but the designers knew damn well that some daring pilots would try to use its jump capability to land on other 'Mechs.
The engineers gave the Highlander impressively thick Lang composite armor on the legs and re-designed the internal skeleton in its feet and lower legs to incorporate hydrolic shock absorption. these tweaks allow the Highlander's actuators to withstand the repeated stress caused by this devastating maneuver.
The jump jets were also re-designed to allow a pilot to automatically redirect the force of his jets to compensate for landing on a moving foe.
Over the years, a Highlander's death from above attack became known as a "Highlander burial". A maneuver which guarantees a light 'Mech will literally be driven into the earth by the force of the Highlander landing on top of it.