Interesting question. Why change tone?
English is called a stress-timed language. In English, we often shift the stress to change from verb to noun as in:
v. produce, n. produce, v. refuse, n. refuse
I wonder if this is also generally true for Chinese? It is worth looking into.
"My understanding for the pronunciation of 將 is 4th tone for verb " you may be a little confused there.
jiāng has a lot of possibilities. Here are some.
- 快要:~要。~至。~来。即~。
- 带领,扶助:~雏。扶~。~军。
- 拿,持:~心比心。
- 把:~门关好。
jiàng does not have so many, but, for simple cases, it is nominal in nature.
1. 军衔的一级,在校以上,泛指高级军官:~领。
2. 统率,指挥:~百万之众。
This link has so many uses for 将 you could get dizzy! There is no clear distinction verb/noun -- jiāng/jiàng
btw is Vibius Vibidius Zosimus really your name?