弱くて

weak and, weak, so

→ 弱い
弱 weak, not strong + く Adverbial form + て Te-form (conjunctive form)
adjective Rare #43,872
weak and, weak, so The て-form of an adjective, used to connect it to what follows or give a reason.
JA: 彼は体が弱くて、よく風邪をひきます。
EN: He is physically weak, so he often catches colds.
Forms of 弱い

弱くて相手にならない

They're too weak to be any competition.

— ダンガル きっと、つよくなる (2016)

あいつ雨の日に弱くてさ

He doesn't do well on rainy days.

— 天気の子 (2019)

彼女は心臓が弱くて…

She has a weak heart…

— 親切なクムジャさん (2005)

この小さなピエロは弱くて小さい

This little clown is weak and small.

— ピエロがお前を嘲笑う (2014)