The English Special should be translated as special, where this adjective refers to the specialized armor of the unit. An example could be a battalion special weapons (Special Weapons Battalion) within the division of the marine corps from the period of the second world war. This battalion was armed with anti-aircraft and anti-tank guns. The battalion was part of the division of special units, and his supervisor degree was the headquarters of the special forces. Post-war example is 4925 cml. a group of special weapons (4925th Special Weapons Group), which dealt with the testing of nuclear weapons.
In the case that the word Special has to express the elite status of the unit, we translate it as special.
In the case that words Special has to express the fact that the unit was entrusted to a non-standard task, we translate also as special..