What does "SPARK " mean?
1:"there was no spark between us"(Feeling/Chemistry)
2:I can’t deny the spark we have together(Chemistry)
3:I felt a spark when I was talking to Sarah(Interest)
4:“I did not intend to spark such a debate with my comment.”(Start)

Vedi una traduzione

In sentences 1. 2 and 3, "spark" means an attraction or intense feeling. I think feeling/chemistry/interest describes it pretty well.
"The first time that I met Thomas, there was an immediate spark and I knew that I wanted to date him"
In sentence 4, spark means to start something.
"I tried to spark up a conversation with my neighbor, but he was not very friendly."
"Thomas likes to spark controversy with his students. He will say anything to make them argue in class."
"Emphatic" is better defined as clear and strong; definite.
"When I asked my daughter if she liked ice cream, she emphatically answered yes."
"The man was emphatic when he denied being drunk."
Yes, blistering means intense or very strong when you are talking about oral exchanges. Think of it as statements that "blister your skin" because they are so mean and strong.
"The two candidates made blistering accusations against each other during the debate."
"When Thomas quit his job, he wrote a blistering letter to his boss listing all of his complaints."