There is a mob in MH by the name of Breelak who gives a quest to find him certain items. However when you try to give them to him you get a 'Breelak can't carry that much weight.' message.
I was told by an Imm who looked into it that his strength is not set high enough and asked to put a post up about it.
Breelak in Mithril Hall
Re: Breelak in Mithril Hall
His strength is set to 144 which seems high enough to cover anything he needs to be given for a quest. Either this has been fixed since the bug report or it was isolated, moving to dead bugs.