I would disagree. I think T2 lockdown is one of the places where Arc Razor really shines. If you catch somebody who only has normal protection on one piece or less of their armor, you will go through them like a hot knife through butter. The Arc Razor is why I abandoned my all defences T2 lockdown loadout. It had Normal/Shadow/Piercing/Elemental/Fire/Poison/Freeze in roughly equal amounts, but I was getting owned by Arc Razors and Sealed/Kamarins.

What Tier lockdown are you playing?

In T2 most people tend to have Normal/Piercing protection so Shadow is very helpful, like the Nightblade (3* Brandish).

If you are playing T3 then the most common protection is Normal/Elemental so a Piercing sword is a good bet, like the Barbarous Thorn Blade or Final Flourish.

*edit* just realized that you said 3* sword so you can ignor my which Tier question as well as the T3 advice.

Is your Arc Razor fully heated? This makes a big difference. Also, try to notice the armor of your enemies that you are having problems with and pick a sword suited accordingly.

Also, the Twisted Snarble Barb is a great choice for T2 Lockdown as well even with many people wearing piecing armor. It is still a very powerful and fast blade.

I've never used one myself (I usually use twisted snarble and sometimes nightblade) but as someone who plays way too much t2 lockdown I have to say the arc razor is not terrible (like the cutter line) but I have never seen anyone truly own a game with one. I've seen twisted snarble, flourishes, nightblades, elemental brandishes, sealeds and kamarins all used to do great things but the best I've ever seen anyone do with the spur line is decent.

The reason for this is it doesn't really have a situation where it excels, snarble and flourish are fast and destroy people with no pierce def, nightblade is great because shadow def is pretty uncommon, elemental brandishes can do status effects and rip people with no elemental def apart, sealed and kamarin are normal type too but they do much more damage and have greater reach than the arc razor. These swords all specialize in one or two areas and as long as you are aware of the weaknesses that they have when you use them you just need to make sure you have a back up weapon for those situations where your sword isn't going to cut it (haha).

Arc razor doesn't have any major weaknesses but no major strengths either so it's a lot harder to do a large amount of damage in any situation so you'll have to hit the other guy more. Who knows maybe you could be the exception but if you want my advice go with one of the swords I listed above.

im t3 and i find the final flourish my favorite choice of weapon its a 2 hit ko for me and its quick for me with no asi and the final lunge is excellent... however most people prefer the barbarthorn version of this piercing sword but its prefrence honestly i enjoy the sparkle at the end of the flourish some like the charge of the barbar but over all these 2 are excellent swords and i recomend them... hope it helped

I'm using an ascended calibur currently and will uprgade to a leviathan

Its amazing easily adaptable to any situation

Since you seemed like you are concerned with Lockdown, I recommend the Grintovec (or upgrades). That is unless, you can get a Faust or Avenger. The Jalovec will have almost the same effect in PvP as Avenger of Faust. it has about the same speed, and seem to have about the same damage due to the Avenger/Faust's split damge and the Jalovec's brute force normal damage.

I use twisted snarble barb to. It's a great sword, and the last in it's line probably has the best charge attack in spiral knights.

dat bomb......is very useful. equip it and the SS and youll be able to k anyone that isnt a guardian quite effectively:
1.drop teh bomb
2.wait for freeze
3.charge SS
4.get behind teh frowzen player ;D
5.???
6.profit. duh.

Keep the tsb.
I think Krannx is referring to having it as a 3rd weapon.
If you don't have a 3rd weapon slot, then make different loadouts with a sword+bomb for when you want to freeze. Equip whatever weapon has the quickest charge to OHKO.

i was using SS an an example, TSB will work just as well, if not better.