Victor is right about Warfare, but I'm under the impression Warfare skills also scale with the weapon (at least the important ones) and if your weapon is a dagger, the skills will receive a bonus from Finesse...
My rogue Sebille uses 2 points in Poly, 10 in Warfare (since it's multiplicative while everything else is additive), some in Necro (Bone Cage, Shackles) and the rest in Scoundrel... Warfare will add the most damage, Necro and Poly provide some utility and Scoundrel adds some damage too. I spent 1 point in Dual Weilding since 3% dodge is nice. I'd recommend you get rid of Huntsman when you can respec. When it comes to skills, Warfare gives you some interesting things, like additional mobility with Phoenix Dive; it also gives Whirlwind (a much needed AOE since Fan of Knives is awful) and A LOT of knockdowns!
Something to note about Scoundrel is that the crit damage it modifies is the final damage, not the chance. Backstabs are always critical hits (so investing in Wits only benefits your initiative) but Scoundrel is kind of important because it increases the amount of damage crits do. For example, at the beggining with 0 Scoundrel, crit hits will deal 150% normal damage iirc, and each point of Scoundrel will add 5% to that final modifier, so all your crit hits (backstabs included) can end up dealing 200% normal damage and perhaps even more, I'm not sure...
About attributes, there's virtually no reason whatsoever for you to invest points in Strenght/Intelligence. You will sometimes find Strenght/Intelligence gear that have nice roguelike stats, but that's the exception and not the rule. The thing about equipment is that each of the types behave differently. Strenght gear will give you high physical armor and low magic armor, Intelligence gear will give you high magic armor and low physical armor, Finesse gear will give you pieces with balance on both physical and magical (values being always lower than the highest of other armors, but higher than their lowest).
While dual weilding, you can gamble with Dodge (using Parry Master and an ally with high Leadership) and focus on your magic armor using Intelligence gear (since Dodge only protects you against physical attacks). To that end, you won't need much Intelligence to equip the parts; the best equipment requires just 14 Intelligence iirc. But there are 2 problems with that approach: 1) Those 4 points in Intelligence means your Finesse is 4 points lower, so a little bit less of damage. 2) Intelligence gear with Finesse/Roguish bonuses are rare, rare like a sword with "+ 1 Two Handed", so keeping your gear appropiate for your level might be quite a challenge.
On the topic of civil abilities, if you are the sneaky thief surely your party has also a "talker/trader" character (a person who handles the convincing of people, buying and selling). Persuasion works in dialogue checks and to get better prices at merchants (so it goes pretty well with Bartering)... So depending on how your party distributes responsibilities, you taking persuasion might not be the best idea (unless you get caught a lot after stealing). But if you want to take it, take it
Civil abilities are fun!
With talents, I really don't know if Guerrilla works with invisibility, but even if it did, I'd still not use it. Mainly because sneaking in combat is not viable as you correctly pointed out and invisibility will work once every several turns (Chameleon Cloak has a long cooldown, invisibility potions are rare and expensive in my experience and you can't really craft them often). But perhaps you can make Guerrilla work! Idk, perhaps devoting your money in buying the ingredients to craft invisibility potions (if invisibility works with Guerrilla).
I find The Pawn much more useful than Executioner when you're not playing with Lone Wolf. Positioning for free is yuuuge when you only have 4 AP to work with. I'd also use Parry Master and Opportunist (yes, when you're behind the target, the attack of opportunity is a backstab!). The rest of the talents are completely up to you. Mnemonic can save you some points in memory (and having more skills is good as long as you don't want an entire hotbar as a rogue lol, I just use 15 memory and I think that's too much for a Warfare/Scoundrel rogue), All Skilled Up and Bigger and Better also have their uses (moar damage!), but you can work with anything except Savage Sortilege, Elemental Affinity, Hothead and the likes since you don't need them.
Finally, don't worry if you regret something on your build! Later in the game you can respec your character at will!!
