Which has more damage with a 2 handed marauder? Critical chances build or going to Iron Grip?

If you can help me guys! I did my own crit chances build but I saw some marauder build which use iron grip which is very useful too! I can make a decision yet but this made me unceartinty! So if you have any tip, share with me! Thanks in advance!

How would iron grip help a 2h marauder at all?