If a character dies to claim that has venomous blade attached, you can't put the venomous blade back into shadows right? since the character (and the blade) both go into morribund during step three right? and you get to trigger responses in step 5, which is too late to put it into shadows.

Yes.

Small timing error, though. Attachments are discarded as a passive game effect of the card they are attached to leaving play (and going moribund). That's why the opportunity to save the attachments is separate from the opportunity to save the character. So if a character is killed in the Resolution step of an effect (Step 3), the attachments are actually discarded in the Passive step (Step 4). The result, of course, is the same since they are both before the Response step (Step 5) where Venomous Blade could be sent back to Shadows.

ahhh alright. thanks. good to know actually. just in case I can exploit it later! lol

I was told there was a lot of sentiment about this card being OP, and possible discussion about it needing to be banned.

Is it really that good? The conversation came up as I was designing a Martell deck w/o it in favor of more characters, locations, and events. In fact, as of right now the deck runs 0 attachments.

its a very good card, yes. no, it shouldnt be banned.