as cosy as a steel razor-blade
 

Hi. I'm a non-native English speaker.
This is a part of a play, Black Comedy written by Peter Shaffer.


CAROL: What about the girl in the photo?

BRINDSLEY: She lasted about three months.

CAROL: When?

BRINDSLEY: Two years ago.

CAROL: What was her name?

BRINDSLEY: Clea.

CAROL: What was she like?

BRINDSLEY: She was a painter. Very honest. Very clever. And just about as cosy as a steel razor-blade.

CAROL: When was the last time you saw her?

BRINDSLEY [evasively]: I told you . . . two years ago.

....................

I can't understand the meaning of this phrase 'as cosy as a steel razor-blade.' Does the word 'cosy' in this context mean she feels comfortable as if she were a steel razor-blade herself?
I would appreciate it if you give me a detailed explanation.
Thank you.

Re: as cosy as a steel razor-blade
 

No - it means "being with her was as comfortable as being with a steel razor blade". In other words that she was a hard, cold person who made cutting comments. In the simile, the qualities of the razor blade are understood to be transferred to the person being described.