noun
Formal or literary term for skillful, fluent speech.
彼の達弁にはいつも感心させられる。
I am always impressed by his eloquence.
雄弁 is more common and neutral for 'eloquence'; 達弁 is a formal/literary synonym.
Compound of 達 (たつ, 'accomplished, skilled') and 弁 (べん, 'speech').