The fonts work fine on my XPERIA Arc (LT15i), so they should on the Arc S (LT18i) and other 2011 XPERIA phones. Maybe they would on other Android devices, too. They're meant for rooted ICS ROMs, and I'm not certain if they would work on Jelly Bean. Still, as a precautionary measure, make sure you take a CWM backup before you flash any of these fonts so you'd be able to recover in case you were to end up in a boot loop.
IMPORTANT: All credits go to LiquidSolstice/Kevin2516 for the flashable zip
. I just did some minor edits to the fonts to have them work with ICS, and replaced the originals in the zip.
Note: If you want to go back to the original font, just flash the Roboto zip that I've included. I'll be uploading more as I create further zips.