Sure, but keep in mind I specifically said that I lost most of the ideas about skills we had ! I'm sure our ideas can still be found somewhere among these forums, but I purposely left those out as I didn't really feel like developing it too much (call it laziness, it's really what it is!)
-I don't think we should add poison damage to the mix... Bleeding damage would be much better, as it makes the zed weaker but don't cause them to panic (which is often counterintuitive in teamplay). It would also make the perk able to inflict two DoT effects AT ONCE.
-I haven't spoken of stunning zeds, only stumbling or staggering them. And in both cases, the idea is mostly to either make it easier to land a critical hit/combo on them, or allow you to flee and heal yourself back up. I believe CC abilities should be kept as Zerk's attributes to further distance the two perks.
-Why would you need an extra skill to increase the critical hit chance?
My point was precisely to GUARANTEE a critical hit if you strike a zed from behind. This encourages you to take risks and count on your team to be a distraction (kinda like having a Heavy distracted by your teammates as you approach to backstab him in Team Fortress 2). I believe a 100% chance to have a critical hit is not OP considering you'd still have to be wary of the other zeds targeting YOU instead of your mates.
-Keep in mind my "bleeding" idea was only a suggestion, not a necessity. I was assuming that all sharp weapons (so everything but the kanabô really) could inflict some bleeding damage, but maybe only under certain conditions (If you land a combo? If you take a specific skill?). As I said, the kanabô would be quite the black sheep of the perk's arsenal, as it's heavier and inflicts blunt damage... Removing the ability to inflict bleeding damage and being slower, but inflicting more damage and being able to smash zeds to the ground !
-Having a special attack for the tantô sounds interesting, but there's absolutely NO weapon that simply gets removed from your inventory as you use them. If you ram your tantô into a zed in the first wave... How will you defend yourself? Maybe it could instead by a whole different weapon, used more like a "tool" similar to the Sentinel or C4. You would have a limited amount of serrated blades that you can jam into zeds so they'll slowly bleed out up until they die or you retrieve your weapon (possibly inflicting some extra damage in the process, at the cost of putting you into melee range...)
-I actually dig the idea of having multiple grenades ! I don't think they should be weapons though, as they're quite clearly tools. I believe they could instead be tied to skills... Or maybe you could have the option to change your grenades directly at the Trader Pod? I could see smoke bombs being used to give you a quick speed boost (3-5 seconds max) and confuse zeds for example. Caltrops could indeed be used to cover your tracks and slow down zeds to make it easier to escape... OR give your team a boost, as you block an entry with those pesky spikes ! Just like a firebug would block a path with a wall of fire, you would instead make it harder for zeds to reach you as they're brought to a sluggish pace by your caltrops.
-I am not fond of having the smoke bombs as "mines" however. I believe they shouldn't be akin to mines at all, and instead be used as a "get out of jail" card if you're in a pinch. I also believe the speed boost should only apply to YOU, while your team would benefit from the confused state of the zeds.