The database is where all of the data, both input by your employees and data collected from your customers, resides. User interfaces, business and application logic, and even employees will come and go, but your data lasts forever. Consequently, enough cannot be said about the importance of building a solid data model from Day One.
Every software architect should know and understand that you can't have it all. It is virtually impossible to design an architecture that has high performance, high availability, a high level of security, and a high degree of abstraction all at the same time. There is a true story which software architects should know, understand, and be able to communicate to clients and colleagues.
Failed projects can happen for a multitude of reasons. One of the most common sources of failure is altering the project schedule in midstream without proper planning. This kind of failure is avoidable, but it can require major effort on the part of multiple people. Adjusting the time line or increasing resources on a project are not normally of concern.
A good architect should lead by example, he (or she) should be able to fulfill any of the positions within his team from wiring the network, and configuring the build process to writing the unit tests and running benchmarks. Without a good understanding of the full range of technology an architect is little more than a project manager. It is perfectly acceptable for team members to have more in-depth knowledge in their specific areas but it's difficult to imagine how team members can have confidence in their architect if the architect doesn't understand the technology.