% inc Physical on weapons doesn't increase spell or warcry damage?

Correct me if I'm wrong, but wands/staves with % elemental damage (%fire/%cold etc) increases elemental spell damage for spell damage.

Meanwhile %phys on weapons doesnt increase the damage of e.g. Corrupted blood support.

the percentage phys on weapons is local to the weapon. meaning it just increases the flat physical damage of the weapon. The attacks that use that weapon will then use its base damages for its damage calculations. Warcrys dont attack with your weapon. They just empower your next attack