12 - you’re mixing up the vowels in an effort to make it ‘Viz’. Think John Prescott R.I.P. (off topic - he saw the new Jag ad and died) or that old tea ad with the monkeys and the piano.
The problem with this puzzle is that most come to it expecting ‘too much’ - the answers are mostly mundane, with only a few ‘choice’ words.
19 - fencing sword.
28 - another anagram (think Toblerone).
[I think all thread’s should be hints and nudges]
[BTW, Trebor, are you anything to the mint company?]