I've really been on the fence about this, I nicked my iron when porting and I definitely feel it when I run my finger across it. I have another one but it has more step wear I don't know what to do

 

Purely by the looks of it, yes it looks unusable. However, if it is not as bad as it looks you may be able to get a machine shop to resurface the whole iron which may work. Others may chime in and give a more technical answer. Post a photo of your other iron and we may be able to give a consensus about it.

A little tip that I have learned from work: When grinding on a surface like that, surround the intended grinding area with multiple layers of yellow Bodyshop masking tape. If you ever slide off or lose control of the tool this gives you a couple layers of protection.