I think this will really exercise your mind in translation. Let's start off with this as there are many closing ones, some good, some not so good.
玉帝興 (行) 兵, 雷鼓雲旗, 雨箭風刀, 天為陣.
Great work! Some comments. Melamine says this poem is from Emperor Chien Lung. We really cannot say this is true or not. It made sense since the Emperor was quite a wily scholar and loved to stump his subjects. This opening couplet also appears in the story of his father's time of the Emperor Yung Cheng killing his general, 年羹堯. So whichever one you want to believe is your choice.
This opening couplet is a metaphor of describing the weather以天化氣象為喻. Fenton's way in translating it as a literal battle scene is also correct. It is his way of seeing how the couplet appeals to him. This group is about poetry appreciation in translation and in doing so; learn more of the source and target languages. We shall be concentrating on this aspect instead. In polishing Fenton's English translation up a bit, we have,
玉帝興 (行) 兵, The Jade Emperor raises (deploys, maneuver) his troops,
雷鼓雲旗, Thunder as war drums, clouds as pennants,
雨箭風刀, Arrows as rain, blades as wind,
天為陣. With the sky as battlefield.
The use of the word “army” or “military” sounds too modern. He added “war”, which did not appear in the original. In this case, it is okay since the first line hints as such. He is trying to paint the scene clearer. I would omit it because it can be a military maneuver instead. Even so, many people will think of an impending war first when 興 is used. “Deploy” has an implication of an impending war. “Maneuver” is neutral.
I like his translation of 陣 as battlefield very much. The translation of this word challenges and vexes me all the time. After many years, I come to terms that “battle formation” is the best especially when translating terms like, 誅仙陣found in stories like “Investiture of the Gods” (封神榜). I chose pennants instead of flags because they are triangular shaped rather than the modern rectangular ones. Perhaps this is due to all the old Chinese movies I saw. Again this is my preference and makes no difference to the meaning. Other than these subtle details, his translation is excellent.
As Datura commented that too much of a fighting image is conveyed. She would rather see less emphaisis on the fighting aspect. I had commented to Fenton earlier that the tone can be softened. He bravely came up with three different versions including one funny weather forecast. Bravo to him. Actually, I was thinking of a simpler solution in using different words. Anyway, here are my “hard” and “soft” translations while sticking closely to the original,
The Jade Emperor maneuvering his troops,
Rolling thunder is his drums and clouds are his pennants.
Thunder rolling like drums, clouds waving like pennants
With rain as arrows and wind as blades.
The rain falling heavily like arrows and winds whistling like swishing blades.
The sky is his battle formation.
太白作詩. 皇帝賜酒. 力士脫靴. 史有證
Your's really one unique kind. So different from the rest. Using the contrast between the fanciful and reality!
太白作詩. 皇帝賜酒. 大臣脫靴. 史有證
Here's another great one from somebody else...
靈猴造反, 虎形龍影, 熊心豹胆, 怒髮為矛 :)