You need a cover enchant, hence the reason many Spirit's Strength people also bring Sight Beyond Sight.
Not having a Rez spell will annoy a ton of people in the RA or similar places.
I just don't know about this build. While yes, it's very fun to get in close and slice&dice with daggers, I just feel that it's adding too many things into a class that isn't particularly suited for close-melee combat.
I feel that in order for those sorts of builds to be effective they often sacrifice much of what makes the single-class so effective in the first place. In the realm of the Assassin, I feel that the absense of Shadow-stepping and the general mobility that they have to be a HUGE disadvantage. One huge reason that you may be getting stomped is that you simply can't kite or move quite like an assassin can; it's much slower to run in and out, no matter how fast Dash may be. Add that to the somewhat low Shadow Arts score (to compensate for the high Spawning Power and Dagger Arts necessities) and you'll find that while yes, you have a strong character capable of impressive numbers, that cannon is simply made out of class...and attached to a ball and chain.
I honestly feel that if you want to get in there and slice&dice, why not just create a PvP assassin? They're a fun class!
However, there are some alternatives that I feel work somewhat better. I'll admit that I did try out the versatility of Spirit's Strength, and the fact that it works with any weapon. I used a Rt/W build using Sword skills and a Rt/A Dagger build, but I felt (probably like you) that it just didn't have the survivability needed. So I tried a few alternatives.
I found that ranged attacks work fairly well, although they have nowhere near the burst capability that the assassin skills do. Both a Rt/R Markshanship build and a Rt/P Spears build worked fairly well. With the Rt/R build, you had the benefit of a larger range (stay away from combat, stay away from the damage). With the Rt/P build, you needed to get closer to the fight in order to connect, but I was also able to use an offhand item (In my case a +5 Armor / +45 HP while enchanted collector item) which I felt added to my survivability. As an added bonus, the slight lack of mobility didn't hurt nearly as bad.
Like a Monk using Smiting Spells in PvE just for a break in the monotony, I'll also use such damage builds just to change things up in PvE. Here's a similar build that I will use for fun when I know that I have other healers around me (read: when I'm with henchmen). It's Rt/P, and the explanation is below.
NOTE: I USE THIS FOR PvE ONLY! PvP PEOPLE BEWARE!
[skill]Swift Javelin[/skill][skill]Barbed Spear[/skill][skill]Disrupting Throw[/skill][skill]Wild Throw[/skill][skill]Vital Weapon[/skill][skill]Sight Beyond Sight[/skill][skill]Spirit's Strength[/skill][skill]Flesh of My Flesh[/skill]
Why do I like this build? Well, it's pretty nasty. Not only do you have the added bonus from Spirit's Strength, you also can put down some nasty debuffs on enemies. You've got your Wild Throw to end stances, your inturrupts via Disrupting Throw, a quick condition spell with Barbed Spear (useful with sword-wielding Heroes), and Swift Javelin, an unblockable attack. It's pretty low on the damage, but it's fun slinging spears around (I actually got the +5 energy spear from Nightfall endgame 'cause it's goofy and fun). Not only THAT, but the animation for a Ritualist to throw spears is absolutely hysterical...we almost throw it submarine-style, underhand! It's quite funny. Oh, and you stay away from the action too, which helps keep you not dead.
There are other builds that I'll use (NOTE: STILL IN PVE) when I feel like doing damage. One of the most deadly that I've found thusfar hasn't been based on Spirit's Strength at all; rather, it uses a combination of Brutal Weapon and Barrage to clump and cream a whole mess of enemies. Try it out; the only two spells that are necessarily vital are Barrage and Brutal Weapon. You fill in the rest (you can add Restoration Magic~)
So yeah. In conclusion, IN MY OPINION:
1) The healing power a Ritualist can put out often dwarfs our offensive capabilities.
2) Barring a Monk, Ritualists are often targetted and called first because other players think we're healmonkies. Without protection, you're dead meat.
3) Without the mobility of an assassin (or protection of a warrior, etc.) it makes you very vulnerable; and without Restoration Magic....)
4) There's no shame in creating a specialized PvP character, and you may enjoy it more
