If App uses breeze and ko validation, I suggest to

add knockout validation rules for every fetched entity as showed in code example (here coffee code implementation for dataPropeties):

addRules = (breezeEntity) ->

    return if breezeEntity.koValidationRulesAdded

    entityType = breezeEntity.entityType        

    for property in entityType.dataProperties

        continue unless property.validators.length > 0

        do (property) ->

            displayName = property.displayName or property.custom?.displayName or property.name

            breezeEntity[property.name].extend

                validation: 

                    validator: (value) ->

                        if breezeEntity.entityAspect.validateProperty property.name, {displayName: displayName, entity: breezeEntity}

                            @message = ""

                            return true

                        else

                            @message = breezeEntity.entityAspect.getValidationErrors(property.name)[0].errorMessage

                            return false

                    message: ""

            return

    breezeEntity.koValidationRulesAdded = true

    return

this code allows:
1) to validate single property with usage of all entity properties and triggers property validation on changes in any properties that validation depends on. For example I can extend entity with fields like password and passwordConfirmation and add custom breeze validator for passwordConfirmation that checks equality of fields.
2) to show validation messages separately for each property in html form using ko binding.