To not have mentioned this?

[SoddingEbay]

My aunt has asked me to sell an item for her on eBay. (Some type of collectable ornament.) However, her DP was "looking" at it and managed to damage it slightly. One of the figures (It's a large piece so this is only a small part of it) has come off and has broken in one place. (It's not noticeable unless you really look). She can easily glue the figure back on the ornament without it affecting it at all.
I've contacted the winning bidder about the damage to the figure but haven't mentioned that it actually came off altogether. I've offered to reduce or refund it by £5 if they still want to purchase.
AIBU not to mention it actually fell off??

I would be completely truthful. Ebay may refund the buyer if the item isn't as described and you will lose out.

If you were the buyer wouldn't you want to be told the truth? If the buyer is not happy wouldn't your rating come down?

If it's a collectable then it may have affected the value, you should be honest

Have sent another message clarifying the extent of the damage. :)

Is it old and how valuable is it? If it's really collectable then any damage at all more or less wipes the value right out. I'd offer a full refund and then relist it as a restoration project.

Yes, you should tell them.