I think a massive miss is a ball carrying midfielder, pace, and creativity from open play. He can play out wide or as a number 10.
I'm not the biggest Siggurdson fan and honestly think he's more of a hindrance to the squad as it is. Nothing suits his strengths. He certainly wouldn't be starting in my attacking 3.
I've made my feelings on Sigurdsson clear plenty of times, but we have to be realistic here. He's not going anywhere, we wouldn't get anywhere near what we paid for him back so we're stuck with him, and we pretty much have to play him. It's a long way from ideal but it's the reality of the situation, and so Shaqiri would be a pointless signing.
I agree we need a ball carrying midfielder but not in the mould of a number 10, more of someone who can transition the play from deep, committing people in the middle of the pitch like Arteta used to, and Barkley did in his last season. It's that which opens up the space for the players further forward, which may allow us to get more out of the attackers we have.