Which set does this bag belong to? Blue and clear orange pieces
Based on the title of the post and Larme’s clarifying comment, you are looking at 59232 Minifig, Weapon Spiked Flail/Mace in a bag with date code 304R7 (which indicates this bag was produced in 2017).



Looking at BrickLink, there are several sets made in 2017 that have this element in Flat Silver (no other color was produced recently). There is one set from 2016 but that set did not come with bags AFAIK. Most are from the Nexo Knights range, but one is from the Super Hero Girls line. If the bag has no large number on it, it must have come from a small set, for example 70361 Macy’s Dropbot Dragon. If the bag does have a large number on it (1, 2, 3 etc) it will be from a larger set. Without more information on what is in the bag besides the Flail, it is impossible to narrow the set down further.

UPDATE: Now that a bag picture has been provided, it is clear this bag belongs to set 70351 Clay’s Falcon Fighter Blaster from the Nexo Knights theme. The Technic connector with hole in the middle in Orange is only in this set (out of all the sets on the list containing the Flail).