Use Raubahn's power at the time the ward ability resolves to determine how much life must be paid. If Raubahn is no longer on the battlefield at that time, use Raubahn's power as it last existed on the battlefield. (If this matters, you must have a very good reason for wanting to pay life.)

If the target Equipment can't legally be attached to the target attacking creature when Raubahn's last ability resolves, the Equipment won't move.