How light is too light for arrows?

[Possum]

I just got my GT Lazer II Pro Series shafts in the mail today. It will be timming them down to 18" , 110 brass inserts, 2" Blazers, plastic nock,(may get aluminum nocks for a little more weight) and will use 125 gr. heads. I haven't assembled any yet but the Gold Tip site calculates the weight of this settup at 386 gr. Using 125 gr heads and 361 gr using a 100 gr head the FOC calculated to around 25%. After I get the arrows assembled I will weigh and check the FOC myself. I will be shooting these arrows from a Matrix 330 and plan to hunt with this settup. I know that Excaliburs says that I am safe as long as I stay at 350 gr or above but it just make me a little leary shooting such a light arrow with that much weight out-front.
I would like some input to put my mind at ease. Iv'e had a splintered carbon arrow through the meaty part of my thumb on my bow hand in my quest for speed with one of my vertical compound bows and dont want to experience that sensation ever again nor do I want to put my matrix under any unnecessary abuse.

Opinions and input please... I am always open to suggestions.

[SEW]

You should be very safe - for the xbow. As poundage goes up, arrow wt should too if a person wants to keep the stress on the xbow the same. A M330 is very lightly stressed compared to a 380 or 405 with the same wt arrow. If the 405 has proven to be durable enough to market with a 350g min arrow , 386gs with a M330 is stressing the bow very little. FWIW, I shoot 396 and 406g arrows out of my 380 & 405.

[Ont_Excal]

That carbon arrow that went through your hand was very likely cracked before you launched it.
All arrows should be flexed and inspected for damage.