I see the points you are making, but you are not seeing mine. I agree that magic can beat out in DES, it was even more powerful than in DAS. But in both games I got tired of hiding behind a veil of superiority....without truly engaging in the fight. Each to their own, therefore you do not need END if you want to take that route....in your OP though you started talking weapons and PVP which insinuates you would like to get dirty as well at least once in while.
THat part aside, it is not relevant to mention your dark grain ring and havels, because equip burden is not the point. The point is that it COSTS endurance....a huge chunk actually, to roll, to swing a sword multiple times, and/or to swing a heavy sword once. It also COSTS a HUGE amount of endurance to block the same from an enemy with your shield (you can hide behind a huge stable shield and incur less endurance....but most get a good shield right away at a low level so the only way to improve further is with END)...this is were you are going to lose your PVP battles if using a melee attack because once you run out of endurance your shield guard breaks, and you can't raise a finger to attack or defend anymore (so even if you are two handing)....basically you get hammered hard when that happens and its usually lights out at that point............unless the opponent is of the same mind as yourself....but as you are finding....majority of people are endurance pigs. ;P
PS - the ring and stuffs that do help are the cloranthy ring which helps end recover faster, along with the grass shield, and the green moss. BUt these only speed recovery...there simply isn't any way to buffer more shots in on O and also block more shots on D without raising END...returns diminish at 40...anything less means some with 40 will pound you, even at a lower level. The returns people get from physical defense and armour PALE in comparison to the returns you get from a larger END bar....plus, you have to go to great lengths to raise both armour and weapons and use a while wack of souls and stones etc. END gives you both attack and defence with one easy payment...its the card of champions!