"You" and "your" refer to a phantom rogue having this class feature.
The Tokens of the Departed feature says, as you have quoted:
While a soul trinket is on your person, you have advantage on death saving throws and Constitution saving throws, for your vitality is enhanced by the life essence within the object.
This "you" can only refer to a phantom rogue having this class feature. If your friends are also phantom rogues, then they should be able to use your soul trinkets. Otherwise, they lack the class feature that allows them to use the soul trinkets.
Compare this to the Chronurgy Wizard's Arcane Abeyance feature:
When you cast a spell using a spell slot of 4th level or lower, you can condense the spell’s magic into a mote. The spell is frozen in time at the moment of casting and held within a gray bead for 1 hour. This bead is a Tiny object with AC 15 and 1 hit point, and it is immune to poison and psychic damage. When the duration ends, or if the bead is destroyed, it vanishes in a flash of light, and the spell is lost.
A creature holding the bead can use its action to release the spell within, whereupon the bead disappears. The spell uses your spell attack bonus and save DC, and the spell treats the creature who released it as the caster for all other purposes.
This feature does not say "while you are holding the bead", rather more generally specifies "a creature holding the bead" - a bead created with Arcane Abeyance can be given to another creature for use.
The Transutation Wizard's Transmuter Stone feature goes even further out of its way to clarify that another creature can make use of the stone:
You can benefit from the stone yourself or give it to another creature. A creature gains a benefit of your choice as long as the stone is in the creature’s possession.
It doesn't get more explicit than that. The trend seems to be that when a subclass has a unique bauble with some features associated with it, the rules are going to tell you it is usable by others, which means the default is probably that it isn't.
To put it another way, the Phantom Rogue has this feature, and this feature says:
You can use soul trinkets in the following ways:
It stands to reason then that the following is true for a character without this class feature:
You cannot use soul trinkets in the following ways:
A creature without this class feature may not be able to hold them at all.
What I'm about to tell you is probably an accurate rules as written ruling, but probably departs from what makes sense. There is an important statement in the feature description that may prevent other characters from holding the trinkets at all:
You can have a maximum number of soul trinkets equal to your proficiency bonus.
Since non-(Phantom Rogues) do not have this class feature, it seems that they would not be able to have any soul trinkets, since it is this class feature which give the Phantom rogue the ability to have a number of them equal to their proficiency bonus. But like I said, while this is RAW, it seems a bit strange.
This raises some questions.
There are some statements in the Tokens of the Departed description that do raise some questions, in light of the ruling I made above. In particular, we see:
- While a soul trinket is on your person...
- ...you can destroy one of your soul trinkets that’s on your person
- As an action, you can destroy one of your soul trinkets, no matter where it’s located.
This third bullet begs the question, "why would the soul trinket be located somewhere else?"
It seems to me that in the first two bullets "on your person" is there only to distinguish between having one or more soul trinkets and not having any at all, without implying that you can give them away.
The third bullet is more difficult to nail down - if there's no reason to give them away, why would they be located somewhere else?
This statement is there to preclude concerns about the action economy of object interaction.
The statement "no matter where it's located" is there to clarify that I don't have to holding my soul trinket to destroy it. I don't have to use my object interaction to draw the soul trinket from my pack into my hand before using my action to destroy it, nor does destroying it require a free hand.