Reima leaves the room where Oscar was lying and travels up the stairs before killing the many hollows up there, he also deals with the armoured one relatively easily by dodging it's obvious attacks and stabbing it through it's open face plate.
He backs away as he looks at the large fog gate, Reima doesn't remember there being an explainable reason for these to exist... Perhaps they allow powerful beings to trap their prey?
Either way Reima intends to go through, jump off the balcony and stab this big demon in the face.
Placing his hand on the fog it allows him to slowly walk through it, he starts humming the DarkSouls battle music as he runs and leaps off the balcony with Arcell's sword pointing downwards towards the demon.
STAB
The Demon gives a loud roar as it thrashes about with Reima still atop it, he decides that the safest place is probably on top of it so he channels Haki into his fingers before jamming them into it's stone like skin to create a hand-hold. As it tries to get him off to crush him Reima is continually stabbing at it's head and neck, with Arcell's sword which he decides to now call Arcell he pierces it's stony skin many times for around 5 minutes until it drops to it's knees and collapsing.
Reima "Easier than I'd thought..." he says as it's soul is dragged towards him and into his chest where the Dark Sign is, it feels like an extra mouth that's slurping on the Demons soul.... Weird.
Picking up the key that had been dropped from the Demon he uses it to open the large doors that lead out of the Asylum. Walking outside the sky is covered by depressing grey clouds that seem to stop any rays of sunlight escaping towards the surface. Reima decides to see if he can get anything from the bird nest that you'd drop items on, as he approaches something speaks.
??? "Want soft, want warm... Give."
Reima shrugs as he get a small amount of Essence and drops it into the nest.
??? "Warm, Soft. Take. After it says this a white orb appears and when Reima inspects it he finds two twinkling titanite.
Reima "Nice. Thank you bird thing..."
It doesn't reply and Reima steps towards the ledge where that giant raven grabs you.
He stands there tapping his foot until he is grabbed by large talons and taken towards Firelink shrine.
The bird drops him roughly next to the bonfire and Reima brushes the dust off of himself as he looks to the man sitting nearby.
Crestfallen Warrior "Well, what do we have here? You must be a new arrival. Let me guess. Fate of the Undead, right? Well, you're not the first. But there's no salvation here. You'd have done better to rot in the Undead Asylum… But, too late now."
Reima "What's your name?" He asks the apathetic man with some irritation in his voice.
Crestfallen Warrior "Youknow.. I think I've forgotten it, a pity..." Reima continues looking at him trying to tell whether or not he's lying. "Don't you have some misbegotten quest to get to? I'd hate to waste your time hehehehe." He starts chuckling out of no where, must've gone mad already.
Reima ignores him and sits at the lit bonfire before trying to increase his level, in the game it was as easy as allocating stats but here he has no idea...
He mediates next to the fire for a couple of hours before he starts trying to feel the DarkSign, he can feel the souls he had absorbed still inside of it like it's some sort of container. He tries to draw some out when some knowledge makes it way into his mind, the knowledge pertains on how to use souls to increase his attributes...
The attributes are :
Vitality : Determines how healthy the body is which effects how much damage it can receive and still be functional, resistance to diseases and organ efficiency and effectiveness.
Attunement : Determines how adaptable to magic the body is, how big the Mana pool is and how easy it is to draw out magic.
Endurance : Determines how much stamina is available, how much weight a body can support and how resistant to bleeding a body is.
Strength : Determines how much power muscles can generate.
Dexterity : Determines how fast the senses are, coordination and overall control over muscles.
Resistance : Determines how resistant to damage the body is, how resistant to poison and other external threats the body may have to deal with.
Intelligence : Determines the capacity and capabilities of the brain, effects your ability to use sorcery formulas, magic manipulation and other intelligence based activities.
Faith : Determines your belief in a god which results in the soul manifesting miracles, with enough Faith casting powerful lightning bolts or healing isn't impossible.
And the hidden stat, Humanity : With enough humanity the body will become more durable, ability to use chaos and for some reason it increases luck as well.
For Reima the best stats to increase would be, Strength, Dexterity, Intelligence and Attunement. Strength and Dexterity to increase his physical capabilities and Intelligence to allow him to cast better spells... One thing he's wary of is Attunement, his body is already inherently magical due to the Elder Blood and he has no idea how it would effect him...
He decides to use the souls to upgrade his Strength first, with his Witcher mutations he is currently fast enough to utilise Stronger muscles and quicker speeds.
To increase your stats with souls you need to concentrate on your goal and Absorb the souls into your own, the reason for this is that your Soul is the template for which your body to grow... Your soul effects you body just as the things your body experiences effects your soul. It's not like training your muscles to be stronger, it's like changing the material that composes your muscles to become stronger. Reima's muscles burn as he increases his Soul level and he starts to meditate to concentrate on the results.
After 10 minutes Reima opens his eyes and checks his muscles, throwing a few jabs and swinging his sword a couple times he comes to the conclusion that the upgrade in strength is not additive but multiplicative... This means with his enhanced Witcher body his abilities will be many times greater than normal a normal undeads. he looks to the side at a large rock that probably weighs 600kg's, approaching it he gets a good grip and lifts it... It's a little difficult to lift it with it's smooth surface but he raises it above his head with moderate ease. He drops it making the ground shudder slightly as the CrestFallen Warrior looks on astonished.
I hope the info dump on how I think soul strengthening works is fun to read, I think this is probably how it works since there isn't any visible change to the musculature of the game protagonist even at 99 strength. I also have some ideas on why you can't increase your stats above 99.
As always, if I missed anything please let me know.