The only way (okay, it's only one way, but the sentence is too long for its content, kinda like Long Dong Silver's claim to fame) to lose the conjunction is to lose the first verb:
Mike inserts a small weapon into his jacket.
Maybe the word pocket should be added: into his jacket pocket.
But this sentence requires some context that allows the reader to know that there are small weapons available for Mike to "take", e.g., prior sentences that say something like this:
Mike reviews his cache of killing instruments: knives, guns, grenades, cellphone-triggered C4 bombs, super-sized Big Macs, and New York City super-sized sodas. He carefully considers his target -- he's short and slim -- and his mission -- "Waste him!" was the way the Company had put it. Mike inserts a small weapon into his jacket pocket....