You are correct that searching for AH records for WWI is difficult because so many of them have been lost. About all that I have been able to find are casualty records at the Czech National Library. They have placed this records on line and you can search them for your ancestor. Here is the link to the site: http://kramerius.nkp.cz/kramerius/Welcome.do
You will have to download a plug-in onto your computer to be able to access the records. The Kramerius welcome page explains how to do that. I will tell you that I did a quick search on the site and did not find anything for a Sawicz Wasyl nor anything for Sawicz Bordulaki. A search of just the surname of Sawicz did surface a number of men with this name but not a Wasyl. Good luck to you.