Hello, GeronaXx!
While the answer to that tends to be yes, there are a few things that may help you judge and get your own decision.
First of all, let's check the formulae of both attack and defense
The formula for attack value is as follows:
L = level, W = weapon attack, S = skill.
Offensive Mode:
Balanced Mode:
Defensive Mode:
The formula for defense value is as follows:
D = shield or weapon defense, S = skill.
If you are wearing a shield, the value of D is the Def value of your shield plus any defense modifier on your weapon. The value of S is your shielding skill.
If you are not wearing a shield, the value of D is the Def value of your weapon (ignoring the defense modifier on it). The value of S is the melee skill that corresponds to your weapon.
Offensive Mode:
Balanced Mode:
Defensive Mode:
Summarizing the formulae above, both damage and damage reduction will be highly influenced by the equipments, so even 1 of attack can make a difference.
That being said, there are another few questions that may be worthy asking yourself before acquiring a new equipment.
1) Do I have money enough to buy it and not compromise my economy?
In this particular case you used as an example, The Stomper is a rare loot from Annihilon and Morgaroth, thus being quite expensive. Arcane Staff not only is cheap but you can acquire yourself by doing the PoI quest (not that hard to get a service nowadays). So if you're the regular Tibia player who don't have lots of money, it is not worthy to change.
2) What are the imbuing slots of both weapons?
Sometimes a weapon with more attack isn't as effective as another with less attack. Imbuing is a main part of the game nowadays and it will affect your damage, heal and profit. In this particular case, both Arcane Staff and The Stomper have the same imbue slots (2).
3) Do I have enough life/defense?
Sometimes you'll be hunting creatures that are tough and if you lose a bit more life you may even die. That being said, in that particular case you may want to prioritize your defense. On the example you set, The Stomper has 10 less defense than Arcane Staff, so in some specific situations you may rather use the Arcane Staff.
In conclusion, even though 1 attack makes difference and you should try upgrading if possible, there are some certain requirements that you may want to think before buying an upgrade. In this particular scenario, I don't think The Stomper is worth buying