Charge Arterial Strike to do damage per round that is not resisted by DR.
Change Invisible Blade's bleeding damage to not be resisted by DR.
(Plenty of mobs have DR, which make these two rather useless.)
Change Opportunist to give a +4 AB when attacking targets that are flat-footed (as well as attacks of opportunity).
Change Skill Mastery to give a +(Rouge Level/3) to Open Lock, Set Trap, Disable Device, Search, and Sleight of Hand checks/rolls in addition to its current effect.
Rouge 5 gives you a special form of Hide in Plain Sight. If you take any other class, this form of Hide in Plain Sight will cease to function. (As hide in plain sight is fairly essential for any sneak attacker in nwn2, this allows pure rouges to have it at an early stage. The trade off is that you cannot multiclass, so if you desire another form of HiPs, you must take a HiPs class to get it.)
New Feats:
I think there are a distinct lack of useful rogue bonus feats (the special feats they get at 10, 13, 16, 19, 24, and 28). So, I have suggested a few more that would definitely be worth taking in order to make the choice between feats a little more difficult. In addition to changing opportunist and skill mastery (as seen above). In addition, I suggest a couple other feats that reward pure rogues and try to give rogues more "rogue-y" things to do instead of just stabbing.
New Feat: Elegant Strike
Can only be taken on a rogue bonus feat.
You can apply your DEX score to damage, as long as you are wielding a weapon that qualifies for weapon finesse. You must have at-least 2/3 Rouge Levels total, or this feat will no longer work. (Similar to monks and insightful strike)
Activation: Automatic
New Feat: Masterful Deception
Can only be taken on a rogue bonus feat. Blackguard 7 gets this feat for free.
You words are like poison to your enemies, filling their heads with lies and deceit. You roll a bluff check equal to 1d20+Rogue Level+1/2 Bluff against a DC of the enemy's HD+Will+1/2 Sense Motive. If the enemy fails, they are confused for 1 round/rogue level. At rouge 25, this impacts all enemies in a large area of effect. If an enemy succeeds, they are immune to any further attempts until they rest. This feat is a full round action and has a 12 second cooldown. This feat does not work on mindless targets.
If the character is blackguard, DC becomes 1d20+2*Blackguard Level+1/2 Bluff.
Activation: Selected
New Feat: Elemental Strike.
Can only be taken on a rogue bonus feat.
You can apply a paste onto your weapon, which empowers it with elemental energy. This feat can be used 2/day, and it lasts 1 hour per rogue level. Each paste increases your damage by 1d4, and you can only apply 1 paste per weapon. When you activate this feat, you can choose which element (acid, fire, cold, electricity) you wish to apply to your weapon. At rogue level 20, this paste deals 1d6 damage. At rogue level 30, this paste deals 1d8 damage.
Activation: Selected
New Feat: Energy Strike.
Can only be taken on a rogue bonus feat. Requires elemental strike. Warrior of Darkness and Anointed Knight both get this feat for free at level 10.
This feat acts like elemental strike, but you can apply energy (Positive, Divine, Negative, or Magical) damage to your weapon instead. This feat can be used 2/day and lasts 2 minutes per rogue level.
Activation: Selected
New Feat: Jagged Strike
Can only be taken on a rogue bonus feat. Requires Arterial Strike.
You lose 3d6 sneak dice. Every time you sneak attack, you deal out 1 damage per remaining sneak dice for a number of rounds equal to half your DEX modifier. This damage cannot be resisted.
Activation: Mode
New Feat: Throat Slice
Can only be taken on a rogue bonus feat.
You lose 1d6 sneak dice. Every time you sneak attack, the enemy must roll a fortitude save (DC=10+DEX Modifier+1/2 Rogue Levels). If the target fails, they are silenced for 3 seconds. If they were casting a spell and that spell was interrupted, they are silenced for 2 rounds. This can only trigger once per round.
Activation: Mode
New Feat: Hamstring
Can only be taken on a rogue bonus feat.
You lose 1d6 sneak dice. Every time you sneak attack, the enemy must roll a fortitude save (DC=10+DEX Modifier+1/2 Rogue Levels). If the target fails, they are slowed for 3 rounds. If they fail a second save, they are paralyzed for 1 round.
Activation: Mode
New Feat: Sunder
Can only be taken on a rogue bonus feat.
You lose 3d6 sneak dice. When you sneak attack, the enemy must roll a fortitude save (DC=10+DEX Modifier+1/2 Rogue Levels). If the target fails, their AC and Saves are reduced by 2.
Activation: Mode
New Feat: Masterful Trapper
Can only be taken on a rogue bonus feat. Hunter can take this feat as a general feat.
You cannot roll lower than a 10 when attempting to disable a device. Additionally, when you set a trap, you tinker with it and are able to make it set off twice (in effect, when you lay a trap you also lay a second one).
New Feat: Bomb Crafter
Given at rogue 10. Techsmith of Gond 10 can take this feat as a general feat and use their caster level in place of rogue levels.
You can craft throwable bombs, which increase in power the more rogue levels you have. A rogue can deliver sneak attacks with these bombs if thrown when the enemy is not engaged in combat. Each bomb requires a ranged touch attack and deals an additional side effect upon a failed save.
Activation: Selected
Given at rogue level 18. Guild Thief gets this for free at level 5.
You can craft thieves tools. The quality of thieves tools you can craft is based on (rogue level/3+2). If you are rogue level 30, you can craft mastercrafted skeleton keys (+20 to open lock) instead. Each set requires 50+(Rogue Level*3) gold to craft.
Activation: Selected
If you are a guild thief, you craft these tools at a 75% discount and can craft 2 per batch instead of 1. Guild Thieves also get +10 to the quality of their thieves tools.
Activation: Selected
New Feat: Double Dipping
Given at rogue level 29.
When you encounter any chest, you can roll a search check with a DC based on the CR of the area you are in. If you succeed on this search check, you can loot a chest one more time before the cooldown sets in.
Activation: Automatic