One can only speculate, but history seems to mark him as nurtured by his mother to be a cruel child, like Jofferey Baratheon from Game of Thrones. This is mostly from an account from when his mother asked him to determine the manner of death for the two Yorkist knights charged with protecting his father, he supposedly ordered their beheading without hesitation.
And that incident can be read in more than one way. Iirc an observer recounted it as follows
Queen - "Fair son, what death shall these men die who you see before you?"
Prince - Are they traitors, Madam?"
Queen - "Yes, my son, they are".
Prince - "Then let their heads be taken off".
To me this passage makes it pretty clear (if the Prince's age -
seven for Pete's sake - were not proof enough) that the whole thing had been well rehearsed beforehand, with the Queen telling Edward that certain traitors were to be haled before him and they should be sentenced to beheading. It sounds to me as if the Prince was a trifle nervous, and afraid he might behead the wrong men by mistake. Hence his question. He wanted to make sure these ywo men really were the "traitors" discussed earlier on. I don't think we need to infer any particular bloodthirstiness.
As for "cutting off heads and making war", quite a lot of young boys (the Prince was now thirteen) were and are fascinated with such things; and Edward, after all, was in training to become a Medieval king, for whom such activities were a normal part of the job description.
Having been brought up (like Richard III) in a time of civil war, he would naturally be interested in things military, the more so as he was supposed to be Henry V's grandson. And he may have reflected that a pacific temperament hadn't done his father any good. As king, I'm afraid he might empty the Treasury by having another go at the French, but one can always hope.