Sword has a .8, .8, and .5(x3) Modifier on its #1 Chain.
GS has a .8, .8, 1.2 Modifier on its #1 Chain
Both have a 2.5 cast time on its #1 chain.
Due to sword having a lower Damage Weapon then GS, sword does a tiny bit less DPS with its #1. Even when you add Right Handed Strength, it can't keep up with GS when you add its CD's.
Its not a factor of being good or bad, its a factor if simple numbers.
Sword has faster attack speed and the 3x hit makes up for the lower damage modifier, seriously some people..
Chain with GS:
744, 744, 1116 (not adding the 3s might) = 2604
Whirling Wrath: 3141 (10 sec cd) (takes 45 sec)
=5745 (It is higher if you can put SoW under your target though, but your targets mostly move around, unless it's a boss.)
but i die just as much as anyone else in a dungeon...
That's your main problem right there, guardian's should always be the last profession standing & chuck-norris the last bits of bosses when the rest of the team dies.
Try to focus more on how you can survive first, then try to keep your team alive.