I played a Guardian since the head start as my main, and he is my go-to guy, as well as my Fractal runner. I run all Knights (with the Knight's Variation for Ascended items - this has Precision as the main stat, instead of Toughness like regular Knights). Ends up with 55ish chance to Crit.
I know you said you run Mace/Sheild and Staff and don't wish to change that. I can respect that, but I will say I use Hammer + Scepter/Focus while keeping a Staff and Shield in my bag for swapping. Staff is next to useless in end-game content and Fractals in general, other than extra speed for Swamp fractal. Hammer is too good to pass up on as a main weapon, dropping tons of boons for your allies (and for Altruistic Healing to proc). Scepter beats Staff for ranged DPS, as well as the Immobilize for certain fractals (Dredge, Shaman). Focus beats Shield because of the Blind, lower cooldowns, and higher DPS.
The build I will link offers lots of Synergy when rolling Hammer + Scepter/Focus, and will keep you at 25 stacks of might almost all the time (in group play, thanks to Empowering Might and Inspired Virtue/Renewed Justice). With Altruistic Healing and the general guide I'll list, you should be pretty hard to kill, offer tons of support and utility to your group, and deal out really good DPS while basically tanking every encounter (thanks to the massive amount of Toughness, boons and DPS).
Build: http://gw2skills.net/editor/?fUMQNAS7dlUgqCnFyvDfIFRuA7DAETBGh/1DHSRGC-e
The general theme here is using Shouts, crits, and combo finishers from your Hammer to toss out tons of Might and basically ALL boons to your party frequently. I keep Might at max stacks and Fury up almost all the time, with tons of tiny heals trickling in constantly. Your F1 (Virtue of Justice) will refresh each time you kill a foe, so you should be spamming this as often as possible (sometimes a LOT, like constantly, as in Dredge fractal). This will not only give you loads of might, but it will Blind nearby foes (thus dealing you less damage, for increased survivability). Blind can also be found on your Focus, and as an added bonus, you apply Vulnerability whenever you apply a blind, increasing your individual and group DPS while decreasing the damage you (and your party) takes. Your Heal (Shelter) also builds Might, as you earn might when Blocking. Your shouts will heal you while buffing yourself and allies. The shouts can be swapped out for Wall of Reflection and Shield of the Avenger when necessary for certain encounters (uncatagorized Fractal, Bloomhunger, etc).
Running this build, I am quite often the last-man-standing in any group, and 99% of the time I have the aggro of the entire room. This allows me to kite quite well, which helps my team do more DPS without worrying too much about defense. I suggest trying this build, you can't really go wrong.
Some notes:
I run 2x Superior Rune of the Monk, 2x Superior Rune of the Water, and 2x Superior Rune of Hoelbrak for Might and Boon duration. These can be swapped for 6x Rune of the Soldier, if you find you can't live without Purity of Voice (Shouts remove Conditions); personally, in group play I find this usually unnecessary, as your heals will offset most condition damage, and your party will occasionally toss out a cleanse as well.
Can't remember my Sigils right now, but I think its Force on my Hammer, and Force/Fire on my Scepter/Focus.
Run Chocolate Omnomberry Cream for precision and Boon Duration, with Crystals for more precision.
Also a note on why the mace is bad for fractals: you will find you very rarely have the opportunity to stand in one place and benefit from the heals. If you're standing still, its because you're using shields and not taking damage, thus rendering a mace obsolete. You'll find most of the utility you like from the mace/shield combo in the Scepter/Focus combo, with more DPS and better skills for most content (and better Synergy in the build).
Sorry for the long post, but I hope this helps. Happy to answer any questions you may have if you decide to try it out : )
