Hi, iam not so experienced vw player but i think i wasn't forced recast my base damage shield after every fight in which thorny shield(lvl 15 scythe style) executed. Now style proc DS rewrite base DS. So few second after fight u are w/o any DS. Am i right ?
And one more question - HP ablative proc in vw's arborial spec line lasted always only 30s ( or until depleted) ? I thought it was 10 minutes. Thanks for clarifying.

Yeah it looks like DA or DS from styles is not co-existing with buffs cast by them or on them by others.