Key PointsBerkshire Hathaway's $1.8 billion stake signals confidence in Tokio Marine.Underwriting discipline helps drive consistent insurance profits.Global operations reduce reliance on Japan's economy.10 stocks we like better than Tokio Marine › When Berkshire Hathaway (NYSE: BRKA) (NYSE: BRKB), the conglomerate Warren Buffett built, invests in an insurance company, the market pays attention. That's exactly what happened in March, when Berkshi…