It just means 'with regard to him' and whatever it is he's doing. It's sort of uncommon to hear, especially with regard to people.

where he's concerned se podría traducir como "en cuanto a él" osea, significa "que tiene que ver con él o con lo que está haciendo". Estoy de acuerdo con Matt, es muy en común.

The phrase "where he's concerned" means "regarding him" or "when it comes to him." Explanation: "I've got no more patience where he's concerned": This means Hershel has run out of patience when it comes to dealing with Shane. It indicates that Hershel is specifically referring to his feelings or actions related to Shane. Paraphrased: "I've got no more patience regarding him." "I've run out of patience when it comes to him." In this context, "where he's concerned" is a way of specifying the subject (Shane) about whom the statement is being made.

Hersell would have no patience if Rick talked to him about Shane in any way.