Those are different words and different entries in the JMdict database. The entry you linked is the SOLE entry for てづよい, while 手ごわい has it's own as well.
While てごわい certainly seems to be the more frequent word, I don't see any indication for archaicness in entries for てづよい. In fact, てごわい is even older (I know that's not a criterion for archaicness).
The 現代新国語辞典, Wisdom JE, 日本国語大辞典, 大辞泉 and probably more, have both words. And they have them separate like JMdict does.
Another major difference between the two seems to be that てごわい is mostly spelled 手ごわい, while てづよい doesn't seem to be used in a mazegaki form at all, mostly appearing as 手強い. Which might've caused confusion as well.
The Luminous JE also has both
I finally got onto my pc and just want to highlight that it's important to directly always ask chatgpt for sources. I often attempt to do some tasks with ChatGPT myself, and for every research related task I get at least 50% made up stuff before I inquire further.
- This reading is extremely rare, possibly archaic, and not standard usage.
You won't find てづよい in most modern dictionaries like:
新明解国語辞典 (Shin Meikai Kokugo Jiten)
広辞苑 (Kōjien)There's really no basis for this. It isn't "extremely rare and possibly archaic"
Outright wrong in 2 ways. Firstly, it is in the 新明解国語辞典 and in the 広辞苑. And not just that, てづよい is in at least 10 monolingual dictionaries, of which four were published less than 5 years ago, and in 4 Japanese-English dictionaries. And secondly, the 広辞苑 is by no means a good representation of modern usage. It has a plethora of archaic and obsure terms.
3 and 4 are meant to be replies to 1 and 2. I structures that weirdly, sorry
Reading and meaning
Below is simply a copy and paste from ChatGPT (I know not always correct but worth looking into it)
Correct Reading: てごわい (tegowai)
This is the standard and commonly accepted reading used in everyday language, literature, media, etc.
Unusual Reading: てづよい (tedzuyoi)
This reading is extremely rare, possibly archaic, and not standard usage.
You won't find てづよい in most modern dictionaries like:
新明解国語辞典 (Shin Meikai Kokugo Jiten)
広辞苑 (Kōjien)
NHK日本語発音アクセント辞典
In practice, native speakers overwhelmingly read and say it as てごわい.
Why does Jisho show both?
Jisho pulls from the EDICT dictionary, which sometimes includes:
Archaic or rare readings
Dialectal variations
Historical uses
So while てづよい might technically exist, it's:
Not standard
Not used in modern speech
Likely to confuse readers if used
Conclusion:
Yes — Jisho listing てづよい as a reading is technically not "wrong," but it's misleading for modern learners. You should absolutely use:
手強い → てごわい（tegowai）