This paper contains potentially offensive and harmful text.Large language models (LLMs) are widely deployed as zero-shot evaluators for answer grading, content moderation, and document ranking.Yet studies show that guard models (Guards)-LLMs fine-tuned for safety-remain vulnerable to "jailbreak" attacks, jeopardising downstream chatbots.We confirm this weakness on three public benchmarks (BeaverTails, XSTest, AdvBench) and trace it to representation shifts that arise in the embedding layer and cascade through the Transformer stack.To counteract the effect, we introduce Gamma-Guard: lightweight residual adapters inserted after the embeddings and at sparse intervals in the model.The adapters start with zero-scaled gates, so they retain the original behaviour; a brief adversarial finetuning phase then teaches them to denoise embeddings and refocus attention.With fewer than 0.1 % extra parameters and only a 2 % latency increase, Gamma-Guard lifts adversarial accuracy from ≤ 5 % to ≈ 95 % a 90 percentage-point gain while reducing cleandata accuracy by just 8 percentage points.Extensive ablations further show that robustness improvements persist across different layer placements and model sizes.To our knowledge, this is the first approach that directly augments large Guards with trainable adapters, providing a practical path toward safer large-scale LLM deployments.

Recently, with the prevalent adoption of blockchain in the financial system, there has been an increasing of anomaly activities such as ponzi schemes, gambling and phishing fraud on Ethereum platforms, and an effective account classification method is urgently required. The existing account classification methods on Ethereum with high accuracy require a learning system to be trained with balanced datasets. However, the distribution of annotated labels for account identities published on third-party sites is relatively imbalanced. Therefore, in this paper, We propose a EthGAN framework which includes a high-dimensional node feature representation module and a few-shot account data augment module to improve the accuracy and robustness at imbalanced datasets. The high-dimensional node feature representation module captures features from statistical, temporal, and transaction structure, and the few-shot account data augmentation module based on generative adversarial network models generate few-shot samples to improve the diversity and representativeness of the training datasets. We conduct extensive experiments to evaluate the performance of our proposed EthGAN framework on real-world Ethereum transaction data. The average classification effect of our method is 10+% higher than that of existing methods. Experimental results demonstrate that our method outperforms state-of-the-art methods in Ethereum account classification.