You will need the Paranoia Soul to access it. Go to the sliding room puzzle, the one where you rearrange a series of 15 square rooms on a grid. You will notice that you can exit this series of rooms at the top right - if you travel there, you will find a mirror. Enter the mirror using the Paranoia soul, and Dracula's Tunic is there.
Chat with our AI personalities
the great axe armours can be found in the condemned tower and you can release souls by talking to Yoko in the village
You need to come up from underneath it, there will be a button to press to blow the ceiling open (which is under the fountain). You'll need to explore though, to be able to access that underground area.
You need the ability soul, Rahab, gained by defeating the boss of that name. His location is the Subterranean Hell, and is actually quite missable since there's only one access point at a time when much of the castle is already open to you. But if you look at the map in the related link, you can guide yourself to his general area and boss chamber.
You must obtain the 'Bone Ark' soul from defeating Bone Arks. When you use it, you will be carried across the room on a platform held by two skeletons. They are unaffected by the spikes, and you will not be injured. Also I believe that you could use the Puppet Master soul, along with Skeleton Ape soul, which will let you throw the doll much further than normal.
Oh, what a happy little question! To get the Black Panther soul in Dawn of Sorrow, you'll need to find and defeat the Cagnazzo enemy in the Subterranean Hell area. Keep painting those happy little strokes and exploring, and you'll find it in no time! Just believe in yourself and enjoy the journey.