I dunno, I found that there are two kinds of skills in Dishonored - meh and overpowered. I already did two playthroughs trying all of them, so I'm kind of burned out otherwise I would have done gone for the "Mostly flesh and steel" achievement. here is a breakdown:
Blink 2 - that's actually more balanced, it tends towards overpowered but it's also meh.
Dark Vision 1 - OP. A legit wallhack plus it shows you the cone of vision of NPCs. Their vision is, like, really bad, knowing how better to avoid it is sort of an overkill.
Dark Vision 2 - wa-a-a-ay more OP. Engage uber easy mode.
Devouring Swarm I - meh. It can distract guards, I suppose. Or you can use other abilities, plus the environment, plus your skills. Sort of redundant. Or you can kill people...that that you can't, you know, stab them or shoot them in the head. Gets rid of corpses, too. If you really need to get rid of corpses that badly, either Shadowkill would be more effective, or you're going to high chaos anyway, so you won't care. Finally, you can use the rats for possession. Yeah... about that - there are enough rats, really, unless you need some in a pinch...in which case you don't need rats.
Devouring Swarm II - the above but it costs 4 more runes.
Possession I there have been about 0 occasions when I've needed to possess something. It's an OK skill but ot as necessary. High manacost made me not use it as much.
Possession II - from meh to OP. Possess somebody, walk him to a secluded place, exit and stab/choke them. Done. At the party, I killed everybody using that tactic. I even had the bone charm that let me drink water to regain mana, so I just possessed them and led them to the toled, then dispatched them and filled my mana.
Bend Time I - meh. Helps you attack, I suppose. Also may help with avoiding attention. Whatever, it doesn't help that much.
Bend Time II - again, from meh to OP. why would you fear fights, when you can just snap your fingers and everybody dies. Or you snap your fingers and disappear. Also, you're virtually undetectable and immune to all security. Easy mode - engage
Windblast I - sort of OK. You can break down doors, as if that was ever needed - you can just go and get the key, too. Or use a rat, if you're into that. Knoocking down foes is OK but that assumes you regularly take on groups of people. It's not like it's hard to evade them. Or sneak by and kills them. Heck, Blink can be used to dispatch groups of foes.
Windblast II - more meh, at least in my experience enemies sometimes survived the impact. Also (not level 2 related but in general) the windblast has very weird way of knocking people around - I was standing behind two people who were facing a cliff, and try as I might I couldn't fling both of them in it. They were about 50 centimetres away from each other, well the edge was about a couple of metres away however, it should have been possible.
Vitality I - big deal or "big deal". Depends if you get in fights a lot or not. OK, it's more like "big deal" or OK-ish. It's 1 rune so it's excused to not really be that impressive.
Vitality II now that, should have been a rune as well. The regeneration is the same regeneration as with mana - when you take damage, there is a tiny sliver of health that would come back if you don't take more damage. That's all. Potions are plentiful, fights and damage are easy to avoid, and the amount of health you'll save up from the regeneration is not significant.
Blood Thirsty I - actually, the only skill I never tried. Both my playthroughs I did stealthy characters - one did stealth massacres (kill everybody trying to not be seen) the other one was a pacifist ghost.
Blood Thirsty II - see above, although I'm thinking it's meh - it only makes fights marginally simpler, you can dispatch foes with Blink anyway.
Agility I - the double jump is awkward but it helps with blinking on high ledges. Not sure, but I think Blink 2 should be able to take you anywhere anyway.
Agility II - I never noticed the difference.
Shadow Kill I - if you want to cheese the game...
Shadow Kill II - if you need that, you don't care for bodies, so you don't need it. Sheesh, a skill that makes itself redundant, how 'bout that.
