The mindset leading to this mastery has several quirks. The most obvious is the insistence on remaining masked. In a pinch dark glasses and a hat will do or a disguise but they do not appear unmasked willingly. Failure to wear a mask deprives them of all their special abilities.
Masked men chose a single weapon to excel in. Pistols are usually taken because they're concealable and quick to use. Bows are also popular. Bazookas and heavy weapons are right out. With their chosen weapon the masked man attacks with +2 to hit and damage (-2 to their roll in The Front). This increases to +3 (-3 to their roll in The Front) to hit and damage at 3rd level (6th in The Front) and +4 (-4 to their roll in The Front) to hit and damage at 5th level (9th in The Front).
Unarmed combat specialists receive the pluses to hit though not damage. Their fists do 1d6 damage . They are also stealthy receiving an additional +1 to surprise (see Surprise below)
Both types can make a called shot. For weapon masters this is fancy shooting such as shooting a pistol out of someone's hand. This does no damage and doesn't get the bonuses above (only the normal THB). Unarmed combat specialists throw a haymaker that will stun their opponent for 1-3 rounds if the target fails a saving throw (Constitution save in The Front).
Masked men surprise their opponents on a 3 in 6 chance. They are +1 to initiative.
Masked men receive a +2 on saving throws to resist mental powers and fear (they roll all Charisma tests with advantage in The Front).
Level XP HD BHB ST
1 2,500 1+1 +1 14
2 5,000 2 +2 13
3 7,500 3+1 +3 12
4 10,000 4 +4 11
5 15,000 5+1 +5 10
A masked man will only kill when it is necessary to save an innocent, ally or themselves. They will never kill an unresisting enemy, preferring to capture them or knock them out. They can't allow innocents to be hurt or killed while they stand by. If they fail in protecting an innocent under their protection they will lose their special abilities unless they immediately work towards avenging that person.