solid nightstalker is the so beloved thief class that gives the pleasures of killing people without they even noticing they are being hunted until is too late or they never found out. That class uses the most Stealth of all weapons going to Silenced .22 pistol to Police Pistols and even melee weapons and Energy Weapons like the Katana and MF Hyperbreeder Alpha
Any One Handed Weapons you want Really they are all well Efficient with the right perks and i suggest the ones i commented on the description
Light Armor or no Armor at all. The best light armor though is the Sierra Madre armor, reinforced
Invest in Perception and Agility they will help you the most especially agility as will make you faster when walking and sneaking.
now there is 3 weapons skills you would want to invest to be a thief but you don't need to invest in all of them just your favorite