What happened to Harry's shield bracelet and his force rings? I don't remember the bracelet getting used up (burned up) in Changes. I don't remember him losing his force rings either. At the end of Changes Harry takes a shower, gets dressed and then has a conversation with Murphy. He then goes back inside the boat, gets tired of waiting inside for Murphy, and goes back outside and gets shot. We don't know if he put the rings or bracelet back on. If Harry didn't put them back on then Murphy or perhaps Thomas has them. Harry had his amulet returned to him in Cold Days, so Mab should have returned the other items too. The only explanation for not returning them is if there is some iron in either the bracelet or rings. Perhaps that might interfere with the Winter Knights mantel or Mab considered anything with iron in it too risky for the Winter Knight to ware.
Another alternative; though not very likely, is that Thomas has Harry's rings and bracelet and he didn't have time to retrieve them in Cold Days. If these items are ever returned perhaps Harry will find his old tools just aren't powerful enough to deal with the new threats he will face. That would be a good reason for Harry to build another lab. Plus, he has to find a way to use Bonnie's knowledge and teach her at the same time. That should be interesting for us and frustrating for Harry. I believe Jim has said that Bonnie has all of Harry and Lash's knowledge but no context to understand it.