Applications of magic

There are, honestly, nearly infinite applications of magic. Some are relatively formalised - you'll see characters refer to Twetherton's Fourth (a method of ritual space creation), or the Forney Variant (to identify magical items.) Some forms of magic benefit from or require objects - wands, working stones, Tarot cards, or the magical journals that allow rapid communication, or the portals that allow direct rapid travel.
There are glamours to fade into the background or keep every eye on you, ways to enchant or affect objects, and all sorts of warding and protective, magics for investigation (check out what the Penelopes get up to), and of course both magical sports (Bohort and Pavo and magical duels.

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Working stones

A number of characters make use of working stones at particular points. They work partially through the principles of sympathetic magic.
These sets can involve a few chosen stones that focus someone's magic for particular incantations or ritual magic (Kate in Wards of the Roses) Or they can be an expansive set used for nuanced and complex diagnosis and magical workings (Rathna and Gabe in The Fossil Door).
There are traditional sets of stones, but they are normally chosen for quality, cut, lack of large inclusions (which can incease a risk of facture in a number of cases), and overall resonance.

Wands

Wands are a supplemental tool - not an essential one. They are complex and fiddly to make, and cost somewhere between a moderately powerful computer and a luxury car in modern financial terms. Since they're not necessary for many kinds of magic, many people don't have one.
However, they can be an incredible advantage for types of magic that involve directing magical intention or focus in a particular area, working at a long distance, or doing some kinds of precise magical scribing in different substances. They're also quite useful for duelling. Wands are generally designed for a specific magical purpose (they are more a specialist tool, not a pocket knife with 15 blades...)
Geoffrey Carillon uses his wand in Outcrossing, and Gabe also has one and uses it in The Fossil Door and in Upon A Summer's Day.

Pleasing tokens

One particular kind of magical object is a Pleasing Token. Country Manners talks about how Kate got the one she wears in Outcrossing.
It functions like a limited Word of Command, encouraging those around the wearer to be agreeable. (Though it does not actually change their minds or intentions, it does make them less likely to act rapidly and aggressively.) There are only a handful known to be in active use at any given time.

Words of Command

These are considered a magical gift from an unknown source - some think it's the land magic, some think it's the Fatae, some think it's divine. There are also more specialised Words, like a Word of Silence. When they are spoken, they affect the person or people they're directed at, at least temporarily (how long depends on a number of circumstances).
Cyrus Smythe-Clive uses a Word of Command and Mabyn Teague uses a Word of Silence in The Hare and the Oak
The Horseman's Word (such as Rufus Pride is mentioned to have in later books) is a specialised form of a Word of Command that works only on horses and other equines.

Words of Command

Some uses described in the books so far (and not mentioned or linked above) include:

• Confirming identity or accuracy of information.
• Creating or calling light.
• Food preservation
• Hygeine and cleansing (people, objects, injuries)
• Identification (of magic, magical patterns)
• Location charms (blood-based and otherwise)
• Offerings and rituals of propriation.
• Protection against weather or other environmental effects (cooling charms in the heat, for example)
• Replaying a series of events (as in Eclipse and On The Bias)
• Truth-telling (or at least knowing that someone is lying)
• Sleep - causing it or encouraging it.