I actually disagree that thieves can easily kill a giant.....assuming your talking about any type of giant warrior. You have to remember that ninjas do get pugil and staff, so that thief is basically fodder for any staff wielding warrior.
you could argue that a backstab + dual backstab might do anywhere from MANGLEs to Demolishes+. But with a giant's hp, that's not really much maybe 100+ dmg at the most. And even with a trap, we'll say out of the 1k+ hp the warrior has, he now has 800ish. So basically with that staff of his, he bashes the thief to death and that's done. Because staff+pugil pwns the thief's dual weapons.
On the other hand, ninjas use strangle to immobilize their opponent before landing blind and usually assassinate. Truthfully, I don't see the ninja ever being used as a melee character even if they can be. Assassinate and study is just too powerful of a combo to need a tone-up to any of their other skills. Granted, if a ninja is unable to strangle their opponent for some reason, just assassinating while hidden is quite effective as well. I've pulled it off a few times w/ sub-pin characters.
The purpose for grapple should be just another skill that lets them put out offensive dmg, the only considerable ones they have are ikuzachi and throw. And caltraps are ridiculously effective for stopping the opponent's feet. When you're down to 0 movement, you're a sitting duck.
well if you guys feel I went wrong somewhere, just chime in.
In the first instance, backstab/dual backstab does way, way more damage than a MANGLE or DEMOLISH. I frequently have done UNSPEAKABLES with my thieves when exploiting a vuln, and easily ANNIHILATES or DISINTEGRATES when not exploiting a vuln. And as any smart thief will generally only attack a tough class when they've already knocked sanc off, the victim is usually forced to flee or stay in battle unsanced. That's where traps come in.
To be honest, I've always thought in a battle of the rogues a thief would have a slight advantage over a ninja. They can sit behind traps, which are difficult for non-thieves to defuse, and often get the critical first strike. In straight melee, a ninja would most likely beat a thief, but with all things considered I've always thought that a thief would have the edge.
In regard to Anoneemus' point about thieves having the ability to de-fly and trip lock giants, while it is technically true, I don't think it's as simple as all that. First off, they have to pick the particular mechanism at 50 which is designed to do that. That's already a big commitment, as it means you're snubbing other mad damage traps. Secondly, I've had that particular mechanism and it fails a lot on anyone who has even mediocre saves.
I do agree, however, that just about anyone at pinnacle will be flying. I never get around without flight with my current pinnacle. Even if you manage to catch someone without flight, it means that the ninja is relying on their enemy to screw up, not on their own skill. I also think that though you may catch someone without flight once, it will be such a rude surprise that you never will again. Much like how once you cleave someone's shield and wail on them, you can bet your arse they'll be burnproofing that thing for all your subsequent fights.
Let's be honest. Flight is not hard to get. Any class that can use staves can get a flight that lasts 48 hours, which is long enough to essentially be permanent. The rest can use scrolls, which have a long duration and are not overly expensive. For the unlucky few who cannot use staves or scrolls, there are alternatives that give flight for the same length of time, if at a slightly greater expense.
I can see how this would greatly gimp a skill which was a real key move for ninjas in the past.