The most common and most likely answer to this crossword clue is the 12 letter word RED-HOTPOKER
I've seen this crossword clue in Financial Times
R
E
D
-
H
O
T
P
O
K
E
R
Buddy explains!
The straight part
We know that "Blooming thing/Edward II’s murder weapon?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case blooming thing/edward ii’s murder weapon? = red-hotpoker.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.