WARNING JUST A THEORY I JUST WANT TO HERE OPINION IM NOT CLAIMING THIS IS TRUE PLEASE DONT REMOVE
ok remember when ginjou said that xcution wanted to give ichigo their powers. after 463 it made me wonder why did ginjou give them ichigos fullbring and then it hit me if their fullbrings fused with ichigos and ichigo will most likely get them back he'll receive their powers to. i also like this idea because think just getting a small portion from one fullbring increased theirs greatly so think if all xcutions powers fused together and with ichigos not to mention with his new buffed up shinigami powers.
Now about ichigos new form i think its different for multiple reasons. 1. ichigos were enahnced by the captains/assistant captains of the gotei 13's reiatsu and 2. rukia said a small portion of his shinigami powers fused with ichigos fullbring so i think that a small portion of his fullbring is mixed with his shinigami powers because he has the bands on his neck and wrists also ginjou mentioned it in 462 that fullbring might have amped his base powers.