Two special weapons you can get hold of are the Scarborough Fair and Love is Blue weapons from Bayonetta and Bayonetta 2.
You’ll need to have a save game for Bayonetta to unlock Scarborough Fair
And a save game for Bayonetta 2 to unlock Love is Blue.
You can then purchase these items from Rodin’s Gates of Hell shop under the Items Tab. Both will cost you 16,999 Seeds.