First what is available (I am using 17%chance while using skill)???

Secondly and most important----

I have recently read that a marks higher than the bow req is pointless as it does not increase the bows damage output. So that being said is the increase of +1 going to creat a huge difference to any skill that it is worth having. I figure I would be lucky to get a max 2 DPs more is it really worth it??

in the end if a marks +1 is worthless is there an offensive grip worth getting??