I'm playing through Dark Souls on the PC. I'm a bit stuck on the first boss, the Asylum Demon. I don't seem to be able to successfully do the plunging attack when I dive off the platform. So I'm having to face him at the bottom with a full health bar. I also appear to be unable to do the kick attack and the forward jump attack. All of these are on RB or RT on the XBox. I'm playing with an old Thrustmaster joypad. I'm wondering if the joypad is the problem. Is anybody playing through on the PC using an XBox controller and is able to successfully pull off these moves?
It could be the controller as I have personally had many old controllers like the thrustmaster and honestly found them to be pretty bad, I cannot really answer if it is the controller as you are the only one with your controller, if anything look at it in the settings (Control Panel > Controllers) and see if the controller reacts to button presses quickly and properly (As in pushing forwards and then letting go doesn't cause you to take a step back.
The second thing is it could be dark souls, dark souls has a certain timing to many of these attacks that take time to get use to. There are delays in swings because your character has to draw their sword back or pull their foot up and kicks requires specific timing.
The timing for the kick is to press the attack button and forwards at the exact same time. Not one slightly ahead of the other but nearly exactly at the same time, the reason is sometimes you want to move forward and attack and not kick so the timing is specific to ensure you kick when you want to kick and attack any other time.
Secondly the plunging attack requires you to not jump off or roll off initially. I don't know if you're doing that but it will delay your attack. Just walk off the ledge at the boss and as soon as you start falling hit the attack button and you should perform a plunging attack. It can actually be done a little too late and seem like you'll miss it only for it to land.
I use a PS3 controller with a tool to make it function like a XBOX 360 Controller and the game reacts perfectly too it and I can perform all these attacks just fine.