Talk is silver, silence is golden. The Silence Rune hushes the critical magic voices. Once embedded to your weapon, attacks will add the Silence status to your targets sometimes, as long as they are not invulnerable to it. It works on many foes and on magic users it does even better as its reputation. The passive effect comes in handy especially when your party is made out of strong fighters who lack on magic defense frequently.
Due to its rarity the Silence Rune is a true collectors item in Suikoden II. Watch out for the Highland soldiers during your mission to the Highland Camp north of Muse. Getting your hands on this rune within Suikoden Tactics can be a bit tricky as well, as you have to precipitate Chiepoo into poverty by helping his enemy in business first, before he starts selling this crystal to you. However, it is your only chance getting one. - Celes