Weapons are tools of offensive capacity. We have no need for these. We are unlikely to ever have "powder" - gunpowder, or even cordite being quite primitive, let alone the rediculousness of firearms in space. That doesn't mean we are sitting targets for erradication. This seriously isn't a topic you've lent much thought. Just unfounded and undereducated fear. Clearly.
This isn't a game of civilisaiton, if it was I would of completed it by now, multiple times. It's also possible to complete that without building any units with offensive capacity, or moving any units outside of your territories. Your inability to relax isn't something we should all suffer for. Any hostile nation attempting to analyse our weaknesses will rapidly give up - before getting to anything that could even remotely be defined as military - or we've done a really piss poor job of designing facilities, systems, policies, procedures etc and will have a lot more serious problems to be concerned with than a nation investing billions into a small scale assault that is inevitably due complete and assured failure.
Pretending to acknowledge the potential existence of other extra-terrestial races, you seem to subscribe a lot of weight to human behaviour and postulate they will conform to the same fallicies. It's highly likely that to of solved the problems with crossing the vast distances of space they would of long previously solved any tendancy to destroy themselves, or probability suggests they would of destroyed themselves a long time before evolving past a stage two civilisation.
If these weapons are not for attacking, what are they for? looking pretty? You have somewhere else to attack other than Earth?
Damn right you won't be attacking Earth - you won't be afforded the opportunity, the easiest way to achieve this being not allowing you the weapon capacity in the first place.
And no, such a weapon would not use 65% of a stars energy. I can envison no way to harvest this. For a start I'd said mass, and it would just abuse it in a way that would effectively kill the star by ejecting it's contents - the precise method used to achieve I feel unwise to discuss with the immature - and in the process mutilate a large part of the solar system, and thorugh lack of gravimetric adherence disperse the rest that survives into the depths of space. I noticed you specifically avoided revealing if such a capacity made you feel safer, knowing that at any minute everything you've ever known is wiped from the face of existence.
An axe is a tool, but a sword is a weapon. One is used to (commonly) chop wood, the other is for causing harm. I do know about civillians, and most would likely be useless in a full scale invasion, IMHO, but the ones who can think or act tactically will be more than enough to do the job. However, to entertain this possibility, the "ship full of soldiers" would require to dock, first. Why would that be allowed? Multiple non-lethal methods could be employed in order to enforce they keep distance, and if somehow no other option was viable, we would be able to use lethal means trivially without actually using "weapons". For example, focusing cutting lasers onto their fuel tanks, centrafugally launching a ten tonne container full of sillicon dioxide into an intercept course... To come close enough to be a "threat" to us, we are a much greater threat to them, being well established and better prepared. The first consideration by anyone thinking of taking such actions.
Lets pretend that the assault attempt could somehow survive our best attempts at mitigation. Attempts to forcibly pressurise the airlocks could be simply dispersed into space, if not added to our tanks - they'll soon run out of atmosphere and be forced to abandon the attempt. Attempts to open the inner airlock without pressurising would be most unwise, to them more than us. We can close the inner and outer airlock again once the pressure has removed(likely destroyed) the ship from our docking port. The requirement to utilse the external surface area as a heatsink in order to disperse the excess thermal energy from significantly populated installations would mean any attempts to breach externally or disable/disrupt systems will slowly cook them, the longer they try it, the more they cook. Considering the radiation sheilding alone is likely to be several meters thick(thicker, if I have anything to say) then cutting their way in is unlikely to be an option, and due to pressure, unlikely to of be much use to them. Spacewalks without tether are commonly unwise, and tethered their distances from the ship should concentrate them in easy to deal with clusters, and the tethers as much as the ship itself becomes a target. If somehow magically our best attempts at mitigation fail and further they are somehow magically able to dock and start moving troops into the facility, then they are concentrated into a single area. Being vastly outnumbered, they could have their weapons - if they are stupid enough to attempt to bring some - simply removed from them with the person(s) securely cable-tied as they attempt to cross the threshold. Any weapon they bring can be easily mitigated, projectile weaponry being unable to compete against various combinations of metal foam and non-newtonian fluids to resist the initial forces and to disperse the penetrative forces. Electricity based attacks mitigated with providing an easier path of conduction than the body, Sonic based attacks commonly mitigated with hearing protection... Anything they can bring to the table has already been mitigated. And if we wanted to use lethal means, the concentrated ingress points make this trivial to mow them like blades of grass.
Earth warfare is none of our concern - beyond encouraging the cessation of such pathetic and unproductive behaviours. Options to provide this encouragement do not include attacking the Earth. Least of all for founding Asgardian ethics of "peacful use of space" - it is not a platform with which to launch an attack on another nation, hostile or otherwise. There's also much better ways of dealing with a fleet of ships than "WMD". Precise methods. And being in the middle of the ocean doens't make it "safe" - the food chain starting in the oceans, much of Earths oxygen created by ocean life and the devestation/pollution of this facet of the ecosystem representing almost a greater threat to the Earth's survival than the idiot incapable of reaching logical conclusions that thought it was clever to posess, let alone use such weaponry, as it impacts all life on Earth, not just civillians, or even humans.
[MOD EDIT] edited to remove offensive remarks As previously mentioned, multiple times, Defence forces are not a military, and the differences are incredibly significant in this case, and as such deserve to be noted.
Your personal (and highly inaccurate) perception doesn't entirely equate to a defacto requirement. Especially when this violates established treaties and even the founding principles on which the nation has been based. I've no intent on waiting for state-enacted holiday where citizens simply celebrate their collective stupidity of replacing one criminally corrupt system with the same thing under a different name and different group of people directly reaping the benefits. I was under the impression that the whole point of Asgardia was to remove ourselves of that sort of thing. As much as removing your own personal fears that lead to irrational behaviours. Evolve.