You have to think of the shield as an Independent object in your arsenal. All of its stats only relate when your shield is up (ie Blocking). It has its own life, defense value, and in of itself immune to status effects. For simplicity, it shares the same types of properties as armor, allowing for a wide enough range of UVs without having to invent several new properties for the shield when it only utilizes 2 (defense and durability).

From a design standpoint, this is a very logical approach compared to most other games that make shields effectively invulnerable, or use an indirectly related stat (like stamina) as the basis for defense. And don't even get me started on games that use shield stats like a piece of armor, but still make you block.

As for shield breaking, it only reduces the damage dealt by how much it was able to absorb before failing, but Status effects don't appear to be reduced in any way. Although the status inflicted by some weapons do seem to be influenced by damage UVs, so the mechanic may apply to shields, but the impact is so minor its difficult to notice a difference.

Also, whats wrong with the tool tip?

that's one of the reasons the owlite shield is popular, beacuse it takes double the amount of hits to break from damage sources that deal shock or fire as well...

Thats is not true. The damage reduction for a resistance bonus is very small in comparison to its base defense. And unless the shield already defends against the base damage type, the bonus from a maxed out resistance will barely add 1 extra hit before breaking.

The main reason the Owlite has wide effectiveness is because it has elemental defense. The 2 most dangerous status inflicting attacks are Gun puppy bullets, and Griever attacks. Both are difficult to evade, so people rely heavily on the shield to defend against those attacks. But the key factor is the extremely high chances of encountering a Gun puppy in nearly every type of level in the game. Since Gun puppy bullets deal elemental damage, along with the ability to attack in volleys, Owlite shields were the natural choice since they could withstand 4-6 bullets, while a non-elemental shield could only take 3 hits before failing. And since status enabled Mechknights deal elemental damage as well, it had great use in any arena.

To counter the high utility of Owlite against gun puppies, they added the Polyp (piercing) and Howlizter (shadow). This allowed more level appropriate turret selection, but had the primary benefit of creating a real threat to the Owlite by replacing certain gun puppy spawns with another damage type.

It's relative to the amount of status damage dealt obviously, not all enemies deal an equivilent amount on every attack; state why you can immune to some status from some attacks but not others ergo you can gain immunity to the fire a Slag Walker's swipe can inflict with enough fire resist but no amount of resist will grant you immunity to its fire breath. Another example would be to compare resistance UVs, an Elemental Max Volcanic Plate Shield will break from an elemental grate in the exact same number of hits as a one without a UV yet despite that will withstand more hits from a gun puppy, because the former deals more damage per hit; enough so that the UV becomes irrelevent. This isn't even factoring in shield regeneration rate which is obviously quite prominent against a lot of enemies, particuarly slower ones.

The major point being made however is that UVs in general don't give a shield a significant amount more resist to anything especially status, and as a general rule are less important than resistances on armour.