Darts, pins and knitting needles on a plane
Darts belong in checked baggage
At a US security checkpoint, TSA does not allow darts in carry-on baggage. Put the set in checked baggage and cover every point so it cannot pierce the bag or injure a baggage handler. A steel-tip dart is not covered by the rule for a small dressmaking pin.
Pins and knitting needles
TSA lists ordinary stick pins and knitting needles as permitted in carry-on and checked baggage. Keep small pins in a closed case or pin cushion, and cover needle tips. If your knitting kit includes a circular thread cutter or another tool with a blade, put that cutter in checked baggage. The needle allowance does not cover its cutting accessory.
Check the contents of the case
Open a craft kit before packing and identify each pointed or bladed tool. A separate pair of scissors needs its own assessment. Protecting sharp tips helps prevent injury during handling, but it does not make a prohibited carry-on item permissible.
Source: TSA: complete item list.