I have been playing a rogue. Weapon focus on bow and daggers. So for the daggers I got (or will get) the One-Handed Perks:

Armsman (5)
Fighting Stance
Savage Strike
Dual Flurry (2)
Dual Savagery

Now I have the Sneak Perks to make sneaking backstab lethal. What I'm talking about here is the face to face melee that ensues after I've taken out one of a group of bandits (for example). I'm thinking that with daggers each of these One-Handed perks helps. What doesn't help, is that 50% of the time my Power Attacks miss. Seems the range is very short for daggers and unless I am right in the guys face while I hold down the mouse buttons (PC) I do a fancy blade dance while the bandit stands back and watches (I'm SURE they are impressed, regardless of what they say).

Anyway what I am looking for is opinions on the option of adding to my arsenal 2 swords also to switch to after a sneak dagger attack and adding the 3 Bladesman perks for those also. Or am I the only one missing half the time with dagger power attacks?

Thanks.

I tend to main hand a sword and off hand a dagger. It's great for when you get detected last second or the Backstab somehow doesn't instant kill.

You will pretty much one-shot everything with backstabs later on. Regarding dragon fights or some of the harder boss encounters, switching to double swords is probably the better choice than to keep daggering them (exception: Shadow Warrior perk!).

However: the improved crit chance by Bladesman are not really worth is, as the crit damage seems to be calculated by only the base damage of weapons.

If I am armed like this, would I still use the dagger (the off hand) in a sneak backstab (and get the x15 bonus)?

Yes

Well I'll be. I guess dualing daggers is kinda dumb anyway then (except for style) if I can still just backstab with my off handed dagger and get the x15 bonus. Thanks for the imput.

Correct, and as someone mentioned above, they do have a much shorter attack range than a sword. When you combine the longer sword range + magnet attacks it is a big difference.

Style points are big with 2 daggers however, You do a dagger flip in your hands with a power attack, so there is that.

I use dual swords and I still get the backstab bonus. (I think)

You'd get the first level 6 x damage attack "Backstab" with any one handed weapon, even maces, but you need a dagger for the second attack "Assassin's Blade" which does 15 times damage.