Well, if you want practical, you can't go wrong with things for fussing over his pokémon. They mean a lot to him, and honestly they're the only way of fighting around here, too, so that's almost the same as training gear.
For personal...I'd give him something related to a shield. You've actually called yourself his shield to me, so...an acknowledgment of that, of your being that for him and being willing to be that for him, would mean a lot. You could go with something that has a shield on it, like an article of clothing or an accessory, or something that just straight up is a shield like a necklace or pin or the like. But it should be something he could wear or carry that'd make him think of you whenever he sees the shield.
no subject
For personal...I'd give him something related to a shield. You've actually called yourself his shield to me, so...an acknowledgment of that, of your being that for him and being willing to be that for him, would mean a lot. You could go with something that has a shield on it, like an article of clothing or an accessory, or something that just straight up is a shield like a necklace or pin or the like. But it should be something he could wear or carry that'd make him think of you whenever he sees the shield.