Since Geralt became Reima's mentor he had broadened the scope of training, giving different combat situations from his own previous experience, Geralt also provided his own knowledge and insight on certain monsters. An example of this would be a common weak point for Ghoul anatomy.
Geralt points to a recently slain Ghoul and starts pointing out he flaws in it's form.
"Ghouls are created from deceased humans, you can see this by the way their spine and limbs are shaped. Now, because we know they come from humans we can also find weaknesses common to humans. Look at it and tell me one."
Reima kneels over the rotting form of the Ghoul, it's doglike appearance unnerving due to the human face clearly attached to it. "The head?"
Geralt shrugs "Obviously, but I'm talking about something more fragile."
Reima "The neck?"
Geralt nods and explains, "Because a Ghouls spine is the same as a humans, just elongated and twisted, you can put a Ghoul out of commission from a well timed strike to it's neck. It has the same number of vertebrae as a human, but because the spine has been mutated it is extremely weak to damage."
Reima "So any strong impact to the spine will likely paralyse them?"
Geralt nods "They travel in packs, so strike the spine and finish it off after the rest are dealt with."
He continues to point out the weakness in it's human like arms and where the vital organs may have shifted during it's transformation.
After they burned the corpse they headed back to eat with the others, Reima smiles as he remembers he will hopefully never have to eat those wild herbs again. Reima speaks with Arie when he can but both seemed determined to learn as much as possible and mine everything they can for knowledge, and while Reima is currently ahead in knowledge and combat Arie still remains competitive.
Geralt had recently been teaching Reima about Signs, their meaning, use and dangers.
Geralt "One of the trainees in my group had blown his fingers off with a misshapen Aard Sign, the idea of something like that was funny to us before that incident, no one else made the same mistake."
Geralt explained how the Signs worked and his interpretation of them after they had travelled to a place of power on the mountain near Kaer Morhen.
"Aard means Force, Direction and Impact. Igni, Fire, Ignite and Burn. Yrden, Trap, Contain, Seal. Quen, Protection, Preservation and Absorption or assimilation depending on how you view it. Axii, Mind, Manipulation and Control. And the hardest Sign that I still don't have a good grasp on, Heliotrop, Stop, Power and Limitation. I will teach you the basic uses of these Sign but it is up to you to meditate on the meanings they embody."
Reima nods and kneels next to Geralt looking over the mountain view while surrounded by lit candles that some how seem immune to the strong breeze. Reima feels like he is being drawn into his mind by a surrounding foreign but familiar force. Geralt never mentioned experiencing anything like this but decided to go with the flow.
He himself still kneeling on the floor but surrounded by hot burning fire. Looking around he sees nothing but pitch blackness and the fire starting to come closer.
Reima tries not to panic but the thought of burning alive scares him more than he would like to admit. He sits still dreading the searing pain he is about to experience. And then.... Nothing, the fire is lukewarm and climbs up his arm. He plays with it, the fire dancing on his palm while he tries to control it but can't seem to make it do anything.
Instead he continues kneeling and starts meditating, fire still enveloping him giving him a dull warmth.
An unknown amount of time later, Reima is awoken by Geralt shaking his shoulder.
"You ok? You've been meditating for seven hours."
Reima "Yeah, It felt like something was talking to me..." Geralt raises an eyebrow at this.
Reima "I think I've understood something." He stands and looks over the ledge and slowly forms the Igni Sign with his fingers trying to draw out the familiar warmth.
Geralt watches as his protege form a perfect Sign even without instruction and unleashing the largest Igni he has ever seen into the air causing a hot breeze to almost push both of them back.
Reima looks back at Geralt and is amused to find the most emotive expression Geralt has ever shown him. Eyes wide open with mouth agape, Geralt tries to voice out something but it gets caught...
They both stand there looking at the embers slowly dispersing from the air.
Reima "Was it any good?" He says with a smug face.
Geralt "Have you been taught this before?" he says trying to regain his composure.
Reima "No... I just felt like that was how Igni should be cast..."
Geralt shakes his head, "Maybe Vesemir will have some answers, come, we have stayed long enough.
They start to walk off the alter when Reima notices the Igni inscriptions lightly carved into the stone. "Will we always train Sign at places like this?"
Geralt nods "Vesemir said that they are more attuned to certain Signs due to the centuries of them being use to train aspiring Witchers." Reima nods realising that places of power aren't just for temporary buffs like in the games but could help him in gaining further understanding of the Signs.
Geralt gets back and drops Reima in the kitchen so he can prepare his meals and tries to find Vesemir. He finds him in the library surrounded by books of all sorts and starting to nod off.
Geralt "Vesemir" He says respectfully trying to wake up the old man.
Vesemir jolts and looks around as he spots Geralt. "Geralt... What can I do for you?"
Geralt pulls up a chair and sits opposite him, "I have started training Reima in the uses of Signs."
Vesemir nods, "Did everything go well?"
Geralt "Yes, very. While we were meditating up at the place of power he managed to form a perfect Igni sign without my instruction and cast a huge fire."
Vesemir nods in understanding. "Yes, some people have an aptitude for magic. Take the school of the griffin for example, they only took in people that were around mage level in power. This caused them to be the most powerful users of Signs that has been recorded. I remember when you first started learning Signs, do you not remember the look I gave you when your started casting?"
Geralts smirk and nods "Like a sailor on a sinking ship." They both laugh as they reminisce on old times past.
As I was writing this I was imagining a Dragonborn running through dungeons spamming Igni signs and shouts. Good thing Signs weren't in Skyrim.
If I missed anything please let me know.