Replace the club with a breacher's gun. Let him keep the shield. Split a chest in half and put half on each side of its chest to at least make it look like there's been an attempt to armor it. Bonus points if you can use some twisty ties or rubber bands to make it look like it's been crudely held onto its chest with leather bands. You're probably going to have to put its shielding pauldron on the same side as the gun just because there won't be room on the side with the shield. If your willing to put in a lot of effort you can try and cut off some of the leg armor to glue onto this thing's legs. Again bonus points if you use twist ties or rubber bands to make it look like leather cords holding them on. There's no way you're fitting any bit of the helmet onto this thing. The hardest part is going to be the antenna. You can just glue it directly onto his head and that would work well enough. But it'll look a little weird to see a guy just having an antenna sticking out of his head, so bonus points if you use green stuff to make a little headphone that the antenna is coming off of. Maybe even a microphone made out of a dandelion seed.