Low reach, low (lower than several 2hs) speed, low damage, animations prone to glancing. Most people are good enough to block several people at once and to block pretty much every feint... also, the 1h left swing is overrated and against bad players you can duck beneath it, you can hiltslash with a 2h/pole with decent damage much faster than a 1h left swing can swing, and if you move into the swing it'll glance if you wear the least bit of armor.
Admittedly I am biased in my view of this as I play a 12/27 light armor 1h pretty purely.
how can u say speed?! crazy
dmg, ofc it has lower damage then a 2 meter big ass sword or polearm, but if you want to dissect you can see that some stabs are innsane, bigger than greatswords so you arent correct here.
left swing hits directly your face, with 100ish speed im dead in less than a second that makes your agi shielder spam 3 swings.
and most of all you dont have to learn to block. right click is all u need, no direction.
mind you i also despise those high level agi stacking 2hers that abuse the shit out of animations but you really cant say board and sword takes more skill than 2h m8