Every day, when donning my tefillin, I (being Ashkenazic) recite two b'rachos, the first one of which is אשר קדשנו במצוותיו וצונו להניח תפלין, said whilst I tie down the shel yad onto my bicep with the strap.

But now I wonder: Isn't the mitzva of tefillin written as "וקשרתם לאות על ידך", in which case the mitzva isn't to place it on the arm (להניח), but rather to tie it on (לקשור). Shouldn't the b'racha reflect that? Shouldn't it be "אשר קדשנו במצוותיו וצונו לקשור תפלין", or "על קשירת תפלין"?

And, assuming there is a reason why it really should be להניח תפלין, why do we still say the b'racha while tying the shel yad; why not while placing the shel yad in the proper position on our arms, as this is what is implied by "להניח תפלין"?