“Women are Exempt from Tefillin...”

In recent times, the baal teshuvah movement has generated numerous halachic questions that have never been dealt with before. It takes a true Torah giant to delve into the sources, find true parallels, and rule.
One woman, after attending an Arachim seminar in Israel, was inspired to become observant. Her husband was not as interested. Although he was not overtly against religion, he was fairly indifferent. Since he seemed slightly interested in the mitzvah of tefillin, his wife asked him to put on tefillin every day.
He answered, “Tefillin are expensive and I am simply unwilling to spend that much money just for a mitzvah.”
The woman was very conflicted about this. On the one hand, she felt certain that if he only had a pair, he would comply and put them on each day without fail. She really wished to just take the money without his permission and purchase a pair of tefillin. After all, he did have an obligation. On the other hand, it wasn’t as if she was obligated in the mitzvah of tefillin and he had to provide a pair for her. Could she purchase tefillin from his money for him?
When she asked this question of her rabbi he had no idea where to even start finding an answer. But he said, “I am not sure but I will ask this question of Rav Yosef Shalom Eliashiv, shlit”a. I will let you know the moment I get an answer.”
When consulted, Rav Eliashiv immediately ruled, “She definitely may not purchase tefillin for him with his money against his will. First of all, it is regarding tzedakah that the Nodah B’yehudah states that a woman may not take money from her miserly husband to give charity when he doesn’t allow her to do so. Although beis din forces one to give tzedakah, who appointed her to oversee this?
Rav Eliashiv concluded, “Besides, in our times, she can procure tefillin free in a gemach and he can put these on. She has absolutely no right to pay for tefillin without his consent.”