I have looked through a few records I have and can find nothing on why the cross is on his grave. I don't remember my grandmother saying anything about it. There are 3 possibilities.
One is it is in reference to his service in the Confederate Army.
A second is it may have something to do with his service in the Texas Revolution.
The third is it is a symbol of the Swedish Rite of the Masonic Lodge. I would have to seek out lodge records to see if he belonged but I do know that the Terrell Lodge in Alto TX, near where he lived, is the oldest Lodge in TX. Also, he was German and may have associated with other Northern Europeans there in Cherokee Co. who may have been members of the Swedish Rite of the Lodge.
Any of these are a possibility. There are no longer any living persons to ask.
My guess is that is most probably the first and a slight possibility of the second.

Thanks

Steve W