“羸敗”一詞在中文中較為古雅，可結合具體語境選擇以下譯法：

1. **直譯保留意象**
- crushing defeat（壓倒性失?。?
- disastrous defeat（災難性潰?。?

2. **強調狀態**
- be utterly defeated（徹底潰?。?
- suffer a debilitating loss（遭受重創的失敗）

3. **文學化表達**
- reduced to impotence（陷入無力狀態）
- enfeebled and defeated（衰弱潰?。?

**例句參考**：
- 敵軍羸敗，倉皇撤退。
The enemy suffered a crushing defeat and retreated in disarray.
- 屢戰屢敗，終至羸敗。
Repeated defeats eventually reduced them to impotence.

根據上下文強弱程度選擇對應譯法即可。