All things in this world have a spirit of some sort. Some are easy to talk to, like people (most of the time). Others, like animals, take some skill. Still others, like plants or even rocks require specialized knowledge to talk to. But there is a commonality to all things: mana flows through them. It is how we talk.
The patient and and skilled listener can hear what the world is telling them. Those that can hear thus become able to speak. So the Pictish Way is to respect the spirit that is present in everything. One then asks the spirits of the world for favors as one needs them. Favors that are paid back.
(Imagine for a moment a group ot Tuath. Folks so purist and so into their little nature spirit thing that they go their own way to commune with the nature spirits on their own. Make it long enough ago that only the elves -- and maybe not all of them -- have any clue that these two are related.)
The oldest example is gathering sling stones. The Pict wades into the water, touching the stones. Those stones that want to journey far from the creekbed (to eventually fly through the air!) will feel different than those that desire to stay. The Pict merely has to ask the stones and hear their answer to find the best ones.
This is indistinguishable from feeling for the shape and heft of the stones that experience has proven will work best.
A more powerful example is "The Lady of The Lake." This goes along quite well with the "scent of tallow candles burning." Think of when you have read fantasy, say for young people, and you got lines like, "And the grim cloak of an evil presence was felt in the forest." That is exactly the type of thing a Pict would be the first to notice. Joe Mage, trainee at Industrial Light and Magic, might not figure out that the pond he just walked by was special. He could generate a tidal wave, or a nice fog cloud to roll in off the pond, but he'd not have a clue that the pond was special unless he ran a site analysis first in prep for setting up the effects he wanted. A pict, on the other hand, would know that this pond was special. He reverently ask to talk to the powerful spirit in the pond. Chances are, if he is any good, the lady of the lake would consent to a chat. She might not hand him a sword and declare him to be King of the Yorkians, but she would give a pleasant chat with the little fellow who asked so nicely.
So the basics boil down to: everything can talk. Everything has a spirit. You should ask things nicely to do what you want or need done. You should return the favor when asked. Or when you see one that needs done that you can do.
Picts are numerically impaired. That do not use substitute words for things that have proper names. They generalize to groups of things. A "herd" of horses is ok. Never "six horses." They can't do math. Money is very very hard for them to deal with. Trade, yes. Money? no.
A pict would be the perfect straight-man in Alice in Wonderland. Talking giant white rabbits? Sure - Want a carrot? Nice kitty...
In general, a pict can only do those things magically that she can ask the spirit of something to do. The answers to a few obvious questions: Illusion/Sound: Not restricted. Mind Control: Sleep is available, most others aren't. Comm/Emp: In general, no. But, a passive version of "Rider Within" is available. Enchantment : Yes. Protection: Yes. Body: Yes, sort of. That is, yes you may cast them, but you must have a willing subject. Knowledge: No. More on this under item B.
The general rule of thumb here is an RP thing: if the GM has any doubt about whether this spell is reasonable, the player should be asked to tell which spirit is being addressed and to phrase the request.
Picts don't have access to Knowledge Spells, per se. You want to know what went on here in the last day or so? Ask the local spirits. No problem. Of course, when you have this capability, there'd be no real need to develop the "technology" of detailed knowledge magic. Just ask the spirits.
The good news is that the Pict can get a lot of the information you'd get from Knowledge spells for free this way, just invest the time to talk to the spirits. The GM should keep a few things in mind, though, when allowing this:
Picts have a strong tendency to be Pacificists. Something about being able to tune into all the vibes of all the little thingies all around you all the time makes a person want to keep those vibes positive.
When it is obvious that something needs to be done -- and especially if a friendly sort of spirit asks you to do something -- you do it. (What goes around comes around.)
Picts don't like to handle worked metal because it tends to pick up the imprint of all the people who worked it. Weapons worst of all; a well bloodied blade has the imprint of violence given and received. Similarly, they do tend to like gemstones. Well, some of them. Gems pick up imprints even better than metal does -- you'll see a pict sort through a pile of stones and pick out certain ones, often with no apparent rhyme or reason. He's picking out the ones that had happy owners -- the ones impressed with positive vibes.
In part because of the lack of refined metal, Picts should always be played with the Primitive disad. That's 3 tech levels below the rest of the world. (I think we were playing that as "they can use fire and a lever, but they don't grok wheels".)
Between the arithmetic problems, and the lack or worked metal, and the tech level, Picts aren't that hard to pick out. They are the dirty little guys, wearing skins, without buttons or other ornaments who trade with gems.
Fast Talking Merchants are hell on Pictish Trade.
Expect Picts to be very heavy in plant/animal sorts of spells. These are the easiest to learn and the things first taught.