We are talking tanking, not hit cap dps gear.
2.7 sec 40 damage weapon. In 5 seconds. Does 40 damage. (14.8 dps weapon)
Same dps of 14.8 on a 1.9 speed if both hit, you would have done 56.27 damage in 3.8 seconds. You do more initial damage to get enough rage for sunder/ other abilities.
You will miss a lot, mentioning + hit gear for low level instance is stupid. You will get dodged, parried, blocked, and miss. Slower weapons are effected by these situations much more than a faster weapon is.