(Go watch 'Anne', the first episode of Buffy Season Three. Pause it right at the end of Scene 15, the conversation between Giles and Joyce. This is what I always figured Giles must have said.)
"She's a young woman who's been placed under any number of burdens, Ms. Summers. Some of them are the same as any other girl her age, but others are absolutely unique, and she has borne them when any number of others would have broken. She's saved my life on more than one occasion, and more than that, she's saved the lives of her friends, of her family, of total strangers and of every man, woman and child in the entire world. I realize that it's a bit hard to take in a phrase like that, so I will repeat it so that you don't miss it.
"Every living being on this planet today owes their life to your daughter. In fact, we all owe her our lives several times over; her courage and skill has saved the entire planet more than once. She saved all these people without thought of the considerable danger to herself, without any wish for reward or recompense, and indeed at great personal cost. If you have to put that into a single word, Ms. Summers, I believe the one I'd select would be 'hero'...and frankly, if you wish to place the 'blame' for that onto my shoulders, I take it as the greatest of compliments. Good day to you."
At which point Giles walks out, leaving Joyce to maybe feel a bit bad about the way she's been handling things.