The last line made no sense to me, but that could just be me. The simplicity was nice, as was the style. Good job.

Any mankind's weak,

^^
I really like this opening. Leaves us with questions of where this is going to go.

but getting strength from weakness
driven by his fears

^^
I think there should be " : " at the end of the second line. I like the last line also but it seems as though it doesn't really connect.

OVERALL;
Ok, this may just be me completely misreading this piece - Haiku's were never my strong point! - but here goes:

To me, you seem to be saying that any one can be weak, especially those who allow themselves to be driven by their fears. BUT man can overcome this fear by not giving in (or being driven) by his fears.

^ Is that right?

The whole piece seems like three disconnected lines - it's not the lines themselves, it's the syllable count not allowing a few more connecting words to be added.

Perhaps try to re-position and re-word slightly the lines such as:

Any mankind's weak
driven by his fears from weakness
can find inner strength

^ Or does that completely misconstrue the meaning?

I don't know.

I do like the idea you're presenting, but it needs a little work with arrangement.

Thats what i thought you meant by the poem.

"The weakness was driven by the fears."

This is a good poem.
It is not very long but it has lots of emotion in it still and could be inspiration to some who need strength.

:)