Feb 23 (Reuters) - u.s. Appeals court revives some claims by charles schwab corp SCHW.N against big banks it accused of libor manipulation -- court ruling 2Nd u.s. Circuit court of appeals says lower court judge erred in dismissing some state law claims, federal securities claims and unjust enrichment claims Schwab and several of its mutual funds had alleged that the banks' libor manipulation caused economic harm Court says schwab purchased more than $40 billion of debt from various bank defendants during the period of alleged libor manipulation