I have been using armor resistance a lot lately, and I'll share some observations.
On maneuvers, 20% armor resistance is what you need to really make a difference on whether a maneuver kills you or not. Perhaps this is because rank 9 torso shots are fatal, whereas rank 7 arnt, and 20% can reduce a 9 to a 7. Not really sure, but in practice I see a big difference on surviving when I have 20% resistance that I just don't see with 10% resistance.
So I think you will have much better results by using the 10% resistance from this event to stack on armor that already has some resistance to obtain 20%+. I echo the suggestion for impact resistance. Lightning resistance may also be a good choice. And impact resistance and lightning resistance cannot be added by a warrior or a ranger, whereas other resistances like crush/slash/puncture/fire/nature/cold can all be added by warriors and rangers typically in a far greater amount than even the highest amount you would be able to reach with this service.
Also some general resistance advice. It does stack ... to protect my legs against earthen fury, I am using 20% full cover impact resistance with 95% full coverage fire resistance, both apply to the leg shots, and on top of that I am wearing leg greaves with 95% cold resistance and 40% cold resistance, and that all applies to the leg shots too. Nothing is halved ... halving is a thing that only can happen to padding, not resistance.
Also, at past events I understand resistance was permitted on shields, and the shield would give full coverage resistance when used. If you add fresh resistance to anything, instead of building up armor that already has a resistance which I recommend, then perhaps a high end shield would be a good choice if permitted at this event.
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