Disclaimer: I'm suspecting a major case of thickness is hiding under this post, I just can't find the relevant game text.

I remember in AG&G that you could give mastery sheets around, without this meaning that you'd lose it for your character if it was still written on the sheet.
Parts of the text of IaWA have me believe that particular strengths still wander around and that one can sometimes write or strike one on/from one's sheet. But I can't find what I have to do if somebody steals a unique object from my character, once the chapter ends. During the chapter: I give the sheet to whichever player whose character stole it, but I keep the object written on my sheet.

Any hints on this? Thanks!

I'm still fond of the rules for when a particular strength is written on your character sheet vs when your character has it but it isn't written on your character sheet, but I wasn't even able to explain them to my group in person, let alone in a rulebook.

I recommend that for all particular strengths you follow the logic of the fiction and apply the mechanics accordingly. For unique particular strengths you'll have to make some calls - I think you should make them as a group, case by case, not beforehand.

-Vincent

Oddly, we never had any problem at all over six sessions using the old rules.

I think the reason is part focus of the game and part procedure: From the first game, the story was often about control of a McGuffin--a cache of Flame Lances, a Magical Key--and the focus on that object, and the process of handing it around, accustomized us to the rules.

More important, I think was physical set-up.  Players would write the particular strength down on a separate card, and add the name to their character sheet as a reminder that you need the card at the beginning of the next session.  I made it clear early on that you only wrote a particular strength on your character sheet at the beginning of a session and that it only came off as part of a negotiation.  During the game, however, whoever had the card--or a copy of the card, if you, say, broke up the Flame Lances--could use it (with the correct Endeavor).  All this was reinforced by slapping the McGuffin card down in the middle of the table at the beginning.

After that we were off to the races.

Check! Thanks guys.