Faint means weak or not strong. The heart is considered the emotional organ so someone faint at heart would be emotionally weak.
The typical meaning of "pass out" is "to faint or lose consciousness." There are other meanings, depending on the context.
meaning a person without no mercy to others and a person that mercy to others.
"With a big heart" means one is sensitive to the needs of others.
"Put your heart into it" means to put as much effort as possible into something.
"Take heart" means to be courageous or hopeful, to think positively
The typical meaning of "pass out" is "to faint or lose consciousness." There are other meanings, depending on the context.
meaning a person without no mercy to others and a person that mercy to others.
The idiom "my heart was in my mouth" means feeling extremely anxious or nervous to the point where it feels like your heart is pounding heavily in your chest.
"With a big heart" means one is sensitive to the needs of others.
To want to have completed a goal.
"Put your heart into it" means to put as much effort as possible into something.
you have broken somone's heart means to hurt someone feelings.
"Take heart" means to be courageous or hopeful, to think positively
It is faint of heart not feint.
Unless there is truly something wrong with your heart, then yes, it is an idiom. My heart fell, my heart exploded, my heart sang, my heart doing anything other than pumping blood is an analogy and an idiom.
This idiom implies that someone's joy and happiness have vanished completely or abruptly. It suggests a sudden and total loss of positive feelings or emotions.
"To be" is not an idiom - it's a verb.