Is hesitation a weakness?
Hamlet's was. So we know at least that it can be, in the classics if not in life. Art imitates life, of vice versa. So there ya go.

Is mine?
Hesitation has certainly lost me plenty of chances at dates and relationships. Heck, even as I started jotting down these words at work I was hesitating to talk to a cute co-worker and to ask my supervisor if I could have some days off to go to a concert.
I did eventually do both, and without an entire royal family getting slaughtered in the interim, so it's probably not what you'd consider a Tragic Flaw. Not in my case anyway. But it has prevented happiness in social situations from time to time.

On the other hand, at least one of the possible relationships spoiled by my shy hesitation to express myself would have turned out to be a one-sided, stifling hell which would have emotionally crippled me, probably severely enough that I never would have escaped from it. (I know this because I've met her current boyfriend, and seen them together.) Subsuming my identity and independance into another person is not what I'd call "happily ever after."
So even though my heart was broken to shards when I found out I would have stood a pretty good chance had I only expressed my feelings sooner, when I look back on things now I'm unbelievably glad that things turned out the way they did. Sure there was a lot of pain then. I cried, I threw stuff around my room, I angsted up every place I went. In short, it sucked and I was miserable for a pretty long time. But some things are worth it. A matter of lesser suffering, you know.

So in some cases the perceived harm caused by hesitation can actually be quite beneficial after all. You'll just never know until way too late for the knowledge to be useful. Probably after the pain's already faded.

I think that situation is the exception, though. Yeah, hesitation is what did save me from being trapped in a subserviant relationship, but a little self-esteem could have too, if I'd had any of it at the time. The difference is that way if I hadn't hesitated, did get into the relationship, and things went the way I think they would have, having some self-confidence could have let me break it off. Hesitation just kept me out of the experience altogether.

So we can probably say that my hesitation IS a weakness or flaw, but it's one of many.
At least it's not lonely.