In my opinion, if a tortoise is free-roaming, he will eat only those items that are ok to eat. He might take a bite of something toxic, but then leave it alone. I feel they instinctively know what is ok to eat and what is not ok.
However, if you are picking weeds for him and adding them to his food, he might just eat them even if they are toxic.
In answer to your question, no, not all weeds are ok to eat.
There are a whole bunch of weeds IDed in the Plant ID section here on the forum. Check it out and see if any look familiar. If you have some different ones over there in the Philippines you can post a pic and see if anybody knows what it is.
Mine will eat creeping charlie every chance they get and it is listed as toxic. I have so much of it, I try to not let them eat it but they get a few bites now and then.