冰与火之歌英文版中的一段,到底怎么翻译?

题目

冰与火之歌英文版中的一段,到底怎么翻译?
Ser Waymar Royce found his fury. "For Robert!" he shouted, and he came up snarling, lifting the frost-covered longsword with both hands and swinging it around in a flat sidearm slash with all his weight behind it. The Other's parry was almost lazy.
came up snarling中 COME UP是什么意思?
in a flat sidearm slash呢?这几个词感觉完全拉不到一起.

答案

came up snarling上火嘛,书面解释是怒发冲冠可以吧,
in a flat sidearm slash斜斜地平削出去