The Missionary is a priestly unit available to the Teutonic Order (and has been available to England in earlier versions of the game). He has a bit of armor and rides a mule, which helps him keep up with fast-moving armies. However, he cannot carry relics, and is also vulnerable to pikemen and other anti-cavalry units.
Available to: Teutonic Order
Trained at: Church
Cost: 75 Florins
Armor/Pierce Armor: 1/0
Special: Converts enemy units, heals friendly units.
Range: Block Printing
Armour: Cistercian Reform (Teutonic Order Unique Technology)
Speed: Mendicant Orders
Hit Points: Celibacy
One should be careful with this unit. He moves faster than a priest, but is still slower than most military units and considered a cavalry unit as well, thus takes extra damage from spear-equipped units. He also has a shorter conversion-range.
There were some bugs with the missionary, but they appear to have been rectified as of 1.72.