I am trying to open the skype .dat hex files and I would like to know if I can use Sublime text instead of the other 'dedicated' hex editors.
Sublime text is one of my favorite editors. You can extend its capabilities by using plugins.
I use its plugin
HexViewer to view hex files. http://facelessuser.github.io/HexViewer/
In Sublime Text, press
p(Win, Linux) or
p(OSX) to bring up the quick panel and start typing Package Control: Install Package. Select the command and it will show a list of installable plugins.
Start typing HexViewer; when you see it, select it.
Restart to be sure everything is loaded properly.
Once the HexViewer is installed in sublime text, press "Ctr + Shift + P" to open the "command palette" now just type "HexViewer: Toggle Hex View", you can now see the hexadecimal code as well.