Allegedly they are/were selling this weapon via mail declaring it as a "keychain" and not declaring it as a weapon, see 1st image. Yes, it's a knuckle duster with attached large protruding knife points, a very dangerous weapon.
I haven't seen the page they were selling it on, it's probably gone since they were banned, but 2nd image you can see their Twitter/X account trying to defend it. "self defence keychain", "ebay sell them too" (no they don't), "legal in the US".
I'm not familiar with the US laws, but even if it's legal to carry bladed/pointed knuckledusters there I'm sure it isn't legal to post them telling the postal service and customs (if it crosses borders, I don't know where they are being posted from) they are "just keychains".
And it goes without saying it's illegal to carry weapons in the UK (including everyday objects carried intended for use as a weapon) and being caught with this thing in the UK would be a go straight to jail card.
So yeah, understandably Patreon want nothing to do with this.