The SIPRI arms trade database is actually good despite its inaccuracies because it at least notes the entries that they were unsure of and has relatively detailed notes.
The US Federal Research Service's Country Study Series (
http://lcweb2.loc.gov/frd/cs/cshome.html) is also a good source, but unfortunately they stopped updating it at the end of the 1980s.
In terms of the Philippines, I would also recommend
http://www.hueybravo.net/index.htm and
http://www.timawa.net/index.htm, but both appear to have basically stopped being updated in 2006. For what you're looking for that might be okay.