Edwin is an English traitor who can be defeated easily.
Below is his typical rectangle-shaped castle with archers on the walls. He mines both iron and stone and produces bread, apples and meat. Some statues are built to raise his honour.
He uses spearmen as his main force. At the beginning of a game, you must prepare for endless waves of spearmen attacks (about 50 troops), and as he starts on 'Baron' rank, he can easily set up smaller forces early. I recommend berserkers or axe throwers against them. He also uses armed peasants for patrol and archers for defense. Some swordsmen are also recruited, but they are used only in sieges.
In sieges he tosses about 80 spearmen, 40 armed peasants, some archers and some swordsmen against you. He uses many laddermen on the walls and occasionally some catapults. The catapults destroy the castle walls and nearby buildings, then melee forces would move in for the kill.
To fight against him, the spearmen and armed peasants can be easily taken out with missile units (axe throwers and crossbowmen are effective). Archers have the range to deal with the catapults, but swordsmen can still reach your walls and cause major damage. Against them you can build traps or fight with melee units.
To defeat Edwin you don't have to build a large army. Several archers, under guard, can deal with most of the troops he uses. The wall with the gatehouse seems to be the weakest to breach in the castle. Destroying his granary can quickly damage his popularity. Without maintaining a work force, his economy suffers.
I dare to say that Edwin is the weakest opponent in Stronghold 2.
*) denotes a former staff member.