Special abilities were added to the game on 12 April 2015, as described in this blog post, http://discworld.starturtle.net/lpc/blog/blog.c?action=filter&blog=recent%20developments&id=584. They boost your abilities in one area of combat, at the expense of another area.
To learn an ability you need to meditate by a statue of a hero. There is usually some requirement to be able to learn the skill.
The statue can be found southeast of the junction of Short Street, Heroes Street and God Street.
Skills required are ???/ being a member of the Warriors Guild. The bonus is ???
The statue can be found in the Sto Lat cemetery at the western edge.
Cas'leb the Merciless (also known as) The Dirty Fighter
You need a skill level of ??? in unarmed fighting to learn the skills. The bonus is ???
The statue can be found at the junction of Genua Avenue and Dauphin Street.
Callus Tacticus (also known as) The Focuser
A sword needs to be sacrificed to the statue before you can acquire any skills. If the sword is regarded as too cheap the sacrifice will be rejected.The bonus is ???
The statue can be found in the front room of the Harbourmaster's office.
Herness Emngwey (also known as) The Pacifist
Skills required are ???. The bonus is ability to defend yourself better at the expenses of attacking.