Perhaps the cultural mavens out there would disagree, but I'll go out on a limb and say that it's traditionally not a manly characteristic to be vulnerable. It's about time we change that perception.
It's actually more studly to see a problem and correct it than to ignore the concept of problems. To assume that if one makes a mistake that one is weak overall is itself a mistake. The true Man is a Righter of Wrongs. Internally and externally. We fix. In order to fix something, it must be somehow broken or in need of improvement at least.
Being vulnerable is essential to growth. Being vulnerable is essential to internal progress. It's a bigger man that says "I've got some issues and I need help". It's a stronger man that does this in front of women as well as men. The beautiful thing is when men get together and admit their vulnerability, and they follow it up with manly actions of change.
I see this all the time in my Junto, and it empowers each and every member to simultaneously allow more personal vulnerability AND help others grow in strength. Show what you might consider a weakness, gather with people who see it for what it really is: a place for growth.
The seeds of all change occur in the vulnerabilities.