Just saw this handheld/portable massager which runs on AAA batteries on sale at Big W.
Keep your expectations in check but I bought one recently for the wife as we found the big AC powered ones to be far too heavy and sometimes too powerful whereas this is more of a gentle vibration style massage with a few different 'heads' to choose from. With no cord and it being relatively lightweight, it's easy to bring with you or leave on a bedside table. My kids also enjoy using it.
This may also be a good inexpensive gift idea for fathers day too.
Funnily enough I actually saw this in Big W yesterday but was shocked at how tiny it is. It looked to be only about 10cm or so.
I can understand your wife's issues with the weight and power on some of the bigger brands/models but I wonder if this would be powerful enough for a man.
Given it's size and being battery powered rather than rechargeable I decided not to buy as, someone who has chronic pain issues, I don't think it would be powerful enough for me.